Method using active stylus and sensor controller, sensor controller, and active stylus

ABSTRACT

A method of using an active stylus and a sensor controller is provided including generally four steps. The active stylus, in response to a trigger indicative of a pen lowering operation, sends refill body information indicating a type of a refill body that forms a pen tip of the active stylus. The sensor controller receives the refill body information and identifies the refill body type of the active stylus. The active stylus repeatedly sends a data signal including a pen pressure value applied to the refill body. The sensor controller derives a position of the active stylus based on the data signal using a position deriving method that corresponds to the refill body information.

BACKGROUND Technical Field

The present invention relates to a method using an active stylus and asensor controller, a sensor controller, and an active stylus.

Description of the Related Art

A position detecting device is known that is capable of sending signalsthrough capacitive coupling from an active stylus (hereinafter may bereferred to simply as a “stylus”), which is a position pointer with abuilt-in power supply device, to a tablet. In this kind of positiondetecting device, one-way communication takes place in which signals aresent from the stylus and received by a sensor controller of the tablet.Patent Document 1 discloses, as an example of such a position detectingdevice, a stylus that communicates data such as pen pressure value,unique stylus identifier (ID), and other information together with aposition signal dedicated for deriving coordinate data.

Patent Document 2 discloses another example of a position detectingdevice. The stylus according to this example includes an electrode forsignal transmission and a battery, and sends results of detection of penpressure in a digital form. Also, the tablet includes a display deviceand a transparent sensor so that both the position pointed to by thestylus and the pen pressure applied by the stylus and the positiontouched by a finger can be detected by the transparent sensor.

Recent years have seen emergence of styluses having a replaceable refillbody (replaceable pen tip) made separately from a stylus housing. PatentDocuments 3 and 4 disclose examples of such styluses.

Patent Document 4 discloses a stylus that detects which one of aplurality of pen tips (refill bodies) is currently placed in the stylus,determines a code indicating an “application feature” (e.g., eraser) fora position detecting device based on the detected refill body, and sendsthe determined code to the position detecting device using an acousticcode. Patent Document 4 also discloses that the stylus detects one outof the plurality of refill bodies based on different arrangements orstructures of metallic contacts between the refill bodies and thestylus, respectively.

PRIOR ART DOCUMENT Patent Documents

Patent Document 1: PCT Patent Publication No. 2015/111159

Patent Document 2: Japanese Patent Laid-Open No. 2014-63249

Patent Document 3: U.S. Pat. No. 8,648,837

Patent Document 4: U.S. Patent Application Publication No. 2014/0168177

BRIEF SUMMARY Technical Problem

In an active stylus, the distribution of electric fields detected by asensor controller may change in accordance with the structure of theelectrode(s) near the distal tip of the refill body (e.g., shape(s),number, and positions of the electrodes). For this reason, it is desiredthat the active stylus can convey, to the sensor controller, the type ofrefill body attached to the stylus in advance.

One possible way of realizing this conveyance would be to sendinformation indicating the refill body type (hereinafter referred to as“refill body information”) from the stylus to the sensor controller.However, the possible communication range via capacitive coupling is nomore than several tens of millimeters. Therefore, it is likely that evenif the stylus detects the attachment of a new refill body and sendsrefill body information on the attached refill body once, theinformation will not be received by the sensor controller. The reasonfor this is that when the refill body is attached, the stylus istypically located away from the sensor controller.

One possible way of ensuring reception by the sensor controller would bethat the stylus repeats the transmission of refill body information anumber of times. When the stylus approaches the sensor controller whilethe transmission is repeated, refill body information is conveyed to thesensor controller as a result. However, the communication bit rate usinga coupling capacity between the electrode at the distal tip of thestylus and the sensor to which the sensor controller is connected islow. Therefore, configuring the stylus to repeatedly send refill bodyinformation may not be effective in terms of utilization efficiency ofcommunication resources.

Therefore, it is an aspect of the present invention to provide a methodusing an active stylus and a sensor controller, a sensor controller, andan active stylus that allow for efficient transmission of refill bodyinformation from the active stylus to the sensor controller.

Technical Solution

A method according to an aspect of the present invention is a methodusing an active stylus and a sensor controller. The method includes astep in which the active stylus sends refill body information indicatinga type of a refill body forming a pen tip of the active stylus inresponse to a trigger generated when a pen lowering operation occurs.The method includes a step in which the sensor controller receives therefill body information and identifies the refill body type of theactive stylus, a step in which the active stylus repeatedly sends a datasignal including a value of pen pressure applied to the refill body, anda step in which the sensor controller derives the position of the activestylus based on the data signal using a method corresponding to theidentified refill body information.

An active stylus according to an aspect of the present invention is anactive stylus configured to be able to send signals to a sensorcontroller and includes a pen tip, a transmitting circuit (transmitter),and a stylus controller. The pen tip has an electrode. The transmittersends signals from the electrode. The stylus controller sends via thetransmitter, to the sensor controller, refill body informationindicative of a type of a refill body that forms the pen tip in responseto a trigger generated when a pen lowering operation occurs. The styluscontroller repeatedly sends via the transmitter, to the sensorcontroller, a data signal after having sent the refill body information.

A sensor controller according to an aspect of the present invention is asensor controller used together with an active stylus configured to beable to send refill body information indicative of a type of a refillbody that forms a pen tip and a data signal including a value of penpressure applied to the refill body. The sensor controller obtains therefill body information sent from the active stylus, determines aposition deriving method corresponding to the obtained refill bodyinformation, and repeatedly derives a position of the active stylusbased on the repeatedly sent data signal using the determined positionderiving method.

Advantageous Effect

According to the present invention, an active stylus sends refill bodyinformation in response to a trigger generated when a pen loweringoperation occurs, making it possible to efficiently send refill bodyinformation from the active stylus to a sensor controller.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a diagram illustrating a configuration of a system accordingto a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a configuration of frame F according tothe first embodiment of the present invention.

FIG. 3 is a diagram illustrating a configuration of a stylus depicted inFIG. 1.

FIG. 4 is a schematic block diagram illustrating functional blocks of astylus controller integrated circuit (IC) depicted in FIG. 3.

FIG. 5A to FIG. 5C are diagrams illustrating variations of a refill bodydepicted in FIG. 3, FIG. 5D is a diagram illustrating a cross section ofa refill body across line B-B depicted in FIG. 5A, FIG. 5E is a diagramillustrating a cross section of a refill body across line C-C depictedin FIG. 5B, and FIG. 5F is a diagram illustrating a cross section of arefill body across line D-D depicted in FIG. 5C.

FIG. 6 is a diagram illustrating a cross section of a refill body holderacross line A-A depicted in FIG. 3.

FIG. 7 is a diagram illustrating configurations of a sensor and a sensorcontroller depicted in FIG. 1.

FIG. 8 is a diagram illustrating a configuration of capabilityinformation CP depicted in FIG. 3.

FIG. 9 is a diagram illustrating details of data format DFmt depicted inFIG. 8.

FIG. 10 is a diagram illustrating a definition of an orientation codeORC depicted in FIG. 9.

FIG. 11 depicts diagrams illustrating examples of the data format DFmtdepicted in FIG. 8.

FIG. 12 is a diagram illustrating a configuration of interactive data DFdepicted in FIG. 3.

FIG. 13 is a diagram illustrating a configuration of noninteractive dataDINF depicted in FIG. 3.

FIG. 14 is a diagram illustrating a flow of operation of the stylusdepicted in FIG. 1.

FIG. 15 is a diagram illustrating a flow of operation of the sensorcontroller depicted in FIG. 1.

FIG. 16 is a diagram illustrating an example of allocation of time slotsto the capability information CP.

FIG. 17 is a diagram illustrating an example of allocation of time slotsto a hash value CP_Hash of the capability information CP.

FIG. 18 is a diagram illustrating an example of allocation of time slotsto the interactive data DF and the noninteractive data DINF.

FIG. 19 is a diagram illustrating another example of allocation of timeslots to the interactive data DF and the noninteractive data DINF.

FIG. 20 is a diagram illustrating an example of allocation of time slotsto the interactive data DF and the noninteractive data DINF when theinteractive data DF includes custom data CD.

FIG. 21 is a diagram illustrating an example of allocation of time slotsand frequencies to the interactive data DF and the noninteractive dataDINF when the interactive data DF includes an orientation OR.

FIG. 22 is a diagram illustrating a modification example of the flow ofoperation of the sensor controller depicted in FIG. 15.

FIG. 23 is a diagram illustrating a flow of operation of the stylus andthe sensor controller according to a second embodiment of the presentinvention.

FIG. 24 is a diagram illustrating a modification example of allocationof time slots.

FIG. 25 is a diagram illustrating a flow of operation of the stylusaccording to a modification example of the present invention.

FIG. 26 is a diagram illustrating a flow of operation of the sensorcontroller according to a modification example of the present invention.

FIG. 27A and FIG. 27B are diagrams illustrating the stylus according torespective modification examples of the present invention.

DETAILED DESCRIPTION

A detailed description will be given below of embodiments of the presentinvention with reference to the accompanying drawings.

FIG. 1 is a diagram illustrating a configuration of a system 1 accordingto a first embodiment of the present invention. The system 1 includes astylus 100 and a sensor controller 31 included in an electronicapparatus 3. Of these, the stylus 100 is configured to include acommunication circuitry 110 having a function to send and receivevarious data (e.g., capability information CP, hash value CP_Hash,interactive data DF, noninteractive data DINF, and beacon signal BS tobe described later). On the other hand, the electronic apparatus 3 isconfigured to include not only the sensor controller 31 but also asensor 30, which forms a touch surface 3 a of the electronic apparatus3, and a system controller 32 (host processor) that controls functionsof the respective circuitry of the electronic apparatus 3 including thesensor 30 and the sensor controller 31. The sensor controller 31 isconfigured to engage in two-way communication with the stylus 100 usingframes by capacitively coupling with the stylus 100 via the sensor 30.

Broken line arrows C1 to C5 in FIG. 1 indicate a typical cycle in whichthe user operates the stylus 100. When using the stylus 100, the useroperates a tail switch 103 (refer to FIG. 3) first and specifies a colorCol and a style Styl (refer to FIG. 8) of a line drawn by the stylus100. The user also replaces a refill body 121 (refer to FIG. 3) of thestylus 100. Then, to actually draw a line, the user lowers the stylus100 (pen lowering operation C1) from a starting point ST outside asensing range SR (range within which the sensor controller 31 can detectthe stylus 100) into the sensing range SR, and further brings the stylus100 into contact with the touch surface 3 a (pen touch operation C2).Then, after moving the stylus 100 in such a manner as to trace a desiredpath on the touch surface 3 a (pen moving operation C3) while at thesame time keeping the stylus 100 in contact, the user raises the stylus100 from within the sensing range SR to outside the sensing range SR(pen raising operations C4 and C5). The user draws a letter or pictureon the touch surface 3 a by repeating a series of these operations C1 toC5. As the user repeats the operations C1 to C5, a condition occurs inwhich the stylus 100 repeatedly moves into and out of the sensing rangeSR of the sensor controller 31.

The sensor controller 31 is a master device that controls thecommunication that takes place within the system 1 and is configured tosend out the beacon signal BS (uplink signal, search signal) that servesas a frame reference time every frame (every frame period interval)using the sensor 30.

FIG. 2 is a diagram illustrating a configuration of frame F according tothe present embodiment, depicting the relation between the frame F, thebeacon signal BS, and a time slot s. As illustrated in the same figure,for example, each of the frames F is made up of 16 (or 32 or othernumber of) time slots s0 to s15, and the beacon signal BS is sent in thetime slot s0 located at the beginning of each frame F. The duration ofeach frame F is, for example, 16 milliseconds (equivalent to 60 Hz) tomatch with a liquid crystal refresh rate. Communication throughcapacitive coupling is narrow band communication, and at most onlyseveral tens of bits (e.g., 20 bits) can be sent out in one time slot.It should be noted, however, that an error detection code (cyclicalredundancy check (CRC)) of several bits may be attached to signals sentand received in the system 1. In this case, the number of bits that canbe sent in one time slot is, for example, 16 bits. The description willcontinue below on the premise that 16 bits can be sent in one time slots.

After sending out the beacon signal BS in the time slot s0, for example,the sensor controller 31 goes on standby to receive a downlink signal DSsent from the stylus 100 in the time slots s1 to s15. When the downlinksignal DS is detected, the sensor controller 31 is configured to derivecoordinate data (X,Y) indicating the position of the stylus 100 by usinga position derivation method that is set corresponding to the type ofthe refill body 121 (refer to FIG. 3) attached to the stylus 100.Specifically, coordinate data (X,Y) are derived based on the positionsof electrodes (plurality of linear electrodes 30X and 30Y illustrated inFIG. 7 which will be described later) of the sensor 30 used to detectthe downlink signal DS and the reception level of the detected downlinksignal DS. The sensor controller 31 is also configured to obtain variousinformation and data that was sent, included in the downlink signal DS,from the stylus 100.

Various information and data included in the downlink signal DS and sentfrom the stylus 100 specifically include the capability information CPillustrated in FIG. 8, the interactive data DF illustrated in FIG. 12,and the noninteractive data DINF illustrated in FIG. 13. Hereinafter, ofthese, the interactive data DF and the noninteractive data DINF may bereferred to as data D. When these pieces of information and data areobtained, the sensor controller 31 supplies these pieces of informationand data to the system controller 32 together with position information(X,Y). The system controller 32 is configured to associate the positioninformation (X,Y), the capability information CP, and the data Dsupplied as described above with each other and supply them to variousapplications such as drawing application via an operating system that isnot depicted. This allows for the position information (X,Y), thecapability information CP, and the data D to be used by variousapplications.

A description will be given here of the outline of the capabilityinformation CP and the data D. A detailed description will be givenseparately later with reference to FIG. 8 to FIG. 13.

First, the capability information CP is information of the stylus 100that may change while the stylus 100 is located outside the sensingrange SR and includes, for example, version information of the stylus100 and a refill body type ID (refill body information) indicative ofthe type of the refill body 121 (refer to FIG. 3) attached to the stylus100. In other words, the capability information CP is information thatremains unchanged while the user is engaged in writing operation usingthe stylus 100. The capability information CP also includes informationthat will never change such as vender identifier that indicates thevendor (e.g., manufacturer) of the stylus 100. The capabilityinformation CP must be known to the sensor controller 31 before variousdata D is sent from the stylus 100 to the sensor controller 31.

The data D is information that has a possibility to change while thestylus 100 is located within the sensing range SR and includes theinteractive data DF and the noninteractive data DINF as described above.

The interactive data DF is, for example, data that changes frequently inthe middle of operation of the stylus 100 by the user, such as penpressure value and pressed state of a barrel button, and is sent fromthe stylus 100 to the sensor controller 31 once or more (commonly aplurality of times) within the single frame F (e.g., 60 Hz) asillustrated in FIG. 18, which will be described later. Also, once a dataformat is determined, the interactive data DF is sent repeatedly in thedetermined data format in the plurality of frames as long as the stylusand the sensor controller detect each other. In principle, the stylus100 periodically and repeatedly sends the interactive data DF in theplurality of frames voluntarily (unilaterally) rather than in responseto polling from the sensor controller 31. A position signal dedicatedfor deriving coordinate data is also included as one type of theinteractive data DF because the pointed position frequently changes withuse of the stylus 100.

The noninteractive data DINF is data that changes less frequently thanthe interactive data DF like a battery level (or data that may beconsidered as changing at such a frequency) and that is sent once everyplurality of frames F (e.g., every several hundred frames). Inprinciple, the stylus 100 sends the noninteractive data DINF in responseto polling (request to send) from the sensor controller 31 rather thanvoluntarily.

FIG. 3 is a diagram illustrating a configuration of the stylus 100. Asillustrated in the same figure, the stylus 100 includes a battery 101,an electrode 102, the tail switch 103, a barrel button 104, an operationstate detection circuitry 105, a stylus controller IC 106, a refill bodyholder 120, and the refill body 121. Also, FIG. 4 is a schematic blockdiagram illustrating functional blocks of the stylus controller IC 106.As depicted in the same figure, the stylus controller IC 106 isconfigured to functionally include the communication circuitry 110, acapability information updating circuitry 111, an interactive dataacquisition circuitry 112, and a noninteractive data acquisitioncircuitry 113.

Referring to FIG. 3, the battery 101 is a power supply device thatsupplies power to drive the stylus controller IC 106 and is configuredto supply a signal that indicates its own remaining capacity level(battery level BL depicted in FIG. 13) to the stylus controller IC 106.

The operation state detection circuitry 105 detects information includedin the interactive data DF and may include, for example, a detectioncircuit that detects a pen pressure value (pen pressure value TiPdepicted in FIG. 12 which will be described later) applied to the distaltip of the stylus 100, and a sensor device such as six-axis inertialmeasurement unit (IMU) that detects an orientation (direction;orientation OR depicted in FIG. 12 which will be described later) of thestylus 100. The operation state detection circuitry 105 is configured tonotify, regarding the sensor device that detects the orientation,information for identifying an orientation code ORC (refer to FIG. 9)indicating the detectable orientation type to the capability informationupdating circuitry 111 in the stylus controller IC 106. It should benoted that the orientation code ORC includes information indicatingwhether or not the operation state detection circuitry 105 has a sensordevice that detects the orientation.

The stylus controller IC 106 is a signal processor configured to processsignals supplied from the respective circuitry of the stylus 100 andsupply signals to the respective circuitry of the stylus 100. A detaileddescription will be given below of functions of the stylus controller IC106 with reference to FIG. 4.

The communication circuitry 110 includes a receiving circuit (receiver)Rx and a transmitting circuit (transmitter) Tx and engages in two-waycommunication based on a plurality of time slots specified in accordancewith the reference time (starting time) of the frame F illustrated inFIG. 2. Describing more specifically, the communication circuitry 110derives the reference time of the frame F by detecting the beacon signalBS using the electrode 102 configured to be integral with the refillbody 121 and sets the reference times of the time slots s0 to s15depicted in FIG. 2 or adjusts synchronization. Then, the communicationcircuitry 110 is supplied with the capability information CP, theinteractive data DF, and the noninteractive data DINF respectively fromthe capability information updating circuitry 111, the interactive dataacquisition circuitry 112, and the noninteractive data acquisitioncircuitry 113 and sends, from the electrode 102, these pieces ofinformation and data in the downlink signal DS in the time slots s1 tos15 that are used for transmission of the downlink signal DS inaccordance with the determined format as depicted, for example, in FIG.9.

The capability information updating circuitry 111 has a function tomanage the capability information CP. Specifically, the capabilityinformation updating circuitry 111 is configured to maintain thecapability information CP in a register (not depicted), update thecapability information CP to match with details of operation of the tailswitch 103 (e.g., number of times switch-ON operation is performed) andreplacement operation of the refill body 121 by the user and supply theupdated capability information CP to the communication circuitry 110.The capability information CP updated as described above includes acolor Col, a style Styl, and a refill body type ID depicted in FIG. 8.

The interactive data acquisition circuitry 112 has a function to managethe interactive data DF. Specifically, each time data included in theinteractive data DF is sent, the interactive data acquisition circuitry112 is configured to obtain each of a pen pressure value TiP, theorientation OR and so on depicted in FIG. 12 from the operation statedetection circuitry 105, and obtain the pressed state of the barrelbutton 104 (barrel button state BB depicted in FIG. 12), and supply thedata to the communication circuitry 110.

The noninteractive data acquisition circuitry 113 has a function tomanage the noninteractive data DINF. Specifically, each time thenoninteractive data DINF is sent, the noninteractive data acquisitioncircuitry 113 is configured to obtain a battery level BL depicted inFIG. 13 and so on and supply the data to the communication circuitry110.

Referring back to FIG. 3, the refill body holder 120 is a member in theshape of a hollow tube that is formed integrally with the housing of thestylus 100 and is configured such that the refill body 121, which formsthe pen tip of the stylus 100, is attachable and detachable. As aresult, the refill body 121 of the stylus 100 is configured to bereplaceable, and the user of the stylus 100 replaces the refill body 121by attaching another refill body 121 to the refill body holder 120 afterdetaching the refill body 121 from the refill body holder 120.

FIG. 5A to FIG. 5C are diagrams illustrating refill bodies 121A to 121C,which are variations of the refill body 121 depicted in FIG. 3. FIG. 5Dis a diagram illustrating a cross section of the refill body 121A acrossline B-B depicted in FIG. 5A, FIG. 5E is a diagram illustrating a crosssection of the refill body 121B across line C-C depicted in FIG. 5B, andFIG. 5F is a diagram illustrating a cross section of the refill body121C across line D-D depicted in FIG. 5C.

The refill bodies 121A to 121C differ from each other in the structureof the integrally configured electrode 102 and the structure of aterminal 123 provided at the proximal tip portion. Describing theelectrode 102 first, the electrode 102 provided in the refill body 121Ais an elongated conductive member that is arranged near and inside thedistal tip of the refill body 121A. On the other hand, the electrode 102provided on the refill body 121B is a conductive member in the shapeformed by hollowing out a truncated cone along the symmetrical axis andis arranged in such a manner as to surround the area near the distal tipof the refill body 121B. The electrode 102 provided in the refill body121C includes two electrodes 102-1 and 102-2. The electrode 102-1 isarranged near and inside the distal tip of the refill body 121C, and theelectrode 102-2 is arranged near and inside the proximal tip of therefill body 121C. The electrodes 102-1 and 102-2 are both conductivemembers in the shape of a rod, and the electrode 102-1 is formed longerthan the electrode 102-2.

The terminal 123 will be described next. Before such description,however, the cross-sectional structure of the refill body holder 120will be described.

FIG. 6 is a diagram illustrating a cross section of the refill bodyholder 120 across line A-A depicted in FIG. 3. As illustrated in FIG. 6,the refill body holder 120 has an approximately circular cross sectionhaving three recessed portions H1 to H3 on its lateral (side) surface.The recessed portions H1 to H3 are arranged 90 degrees apart in sequencestarting with the recessed portion H1. Terminals T1 to T3 are providedrespectively at the recessed portions H1 to H3. The terminal T1 isconnected to terminal D1 via a buffer, the terminal T2 is grounded, andthe terminal T3 is connected to terminal D0 via a buffer. The terminalsT1 and T3 are also connected to power wiring that is supplied with asupply potential Vdd via a resistive element. It should be noted thatthe terminals D0 and D1 are input terminals of the stylus controller IC106 as illustrated in FIG. 3, and signals input to the terminals D0 andD1 are supplied to the capability information updating circuitry 111 asdepicted in FIG. 4.

Referring back to FIG. 5, as illustrated in FIG. 5D to FIG. 5F, each ofthe refill bodies 121A to 121C has an approximately circular crosssection having three projected portions. These projected portions areconfigured to fit into the recessed portions H1 to H3 depicted in FIG.6.

In the refill body 121A depicted in FIG. 5D, the terminals 123 areformed at two of the three projected portions corresponding to therecessed portions H2 and H3. These two terminals 123 are connected toeach other by a wiring segment L1. When the refill body 121A is attachedto the refill body holder 120, the two terminals 123 corresponding tothe recessed portions H2 and H3 are brought into conduction with theterminals T2 and T3, respectively. As a result, a ground potential issupplied to the terminal T3, causing a high level (1) to appear on theterminal D0. On the other hand, a low level (0) appears on the terminalD1 corresponding to the terminal T1 to which the terminal 123 is notconnected. The capability information updating circuitry 111 isconfigured to detect the refill body type ID “01” of the refill body121A from the potential levels “0” and “1” supplied to the terminals D1and D0 as described above.

In the refill body 121B depicted in FIG. 5E, the terminals 123 areformed at two of the three projected portions corresponding to therecessed portions H1 and H2. These two terminals 123 are connected toeach other by a wiring segment L2. When the refill body 121B is attachedto the refill body holder 120, the two terminals 123 corresponding tothe recessed portions H1 and H2 are brought into conduction with theterminals T1 and T2, respectively. As a result, a ground potential issupplied to the terminal T1, causing a high level (1) to appear on theterminal D1. On the other hand, a low level (0) appears on the terminalD0 corresponding to the terminal T3 to which the terminal 123 is notconnected. The capability information updating circuitry 111 isconfigured to detect the refill body type ID “10” of the refill body121A from the potential levels “1” and “0” supplied to the terminals D1and D0 as described above.

In the refill body 121C depicted in FIG. 5F, the terminals 123 areformed at all of the three projected portions. The terminals 123 areconnected to each other by a wiring segment L3. When the refill body121C is attached to the refill body holder 120, the three terminals 123corresponding to the recessed portions H1 to H3 are brought intoconduction with the terminals T1 to T3, respectively. As a result, aground potential is supplied to the terminals T1 and T3, causing a highlevel (1) to appear on both the terminals D1 and D0. The capabilityinformation updating circuitry 111 is configured to detect the refillbody type ID “11” of the refill body 121A from the potential levels “1”and “1” supplied to the terminals D1 and D0 as described above.

FIG. 7 is a diagram illustrating a configuration of the electronicapparatus 3. As illustrated in the same figure, the sensor 30 isconfigured so that a plurality of linear electrodes 30X and a pluralityof linear electrodes 30Y are arranged in a matrix fashion, and thesensor 30 is capacitively coupled with the stylus 100 by these linearelectrodes 30X and 30Y. Also, the sensor controller 31 is configured toinclude a transmitting circuit 60, a selecting circuit 40, a receivingcircuit 50, a logic circuit 70, and a micro controller unit (MCU) 80.

The transmitting circuit 60 is a circuit for sending the beacon signalBS depicted in FIG. 1. Specifically, the transmitting circuit 60 isconfigured to include a first control signal supply circuit 61, a switch62, a direct spreading circuit 63, a spreading code holding circuit 64,and a transmitting guard circuit 65.

The first control signal supply circuit 61 retains a detection patternc1 and has a function to continuously and repeatedly output thedetection pattern c1 during a given continuous transmission period(e.g., 3 milliseconds) and to output an end pattern STP in accordancewith the instruction of a control signal ctrl t1 supplied from the logiccircuit 70.

The detection pattern c1 is a symbol pattern used by the stylus 100 todetect the presence of the sensor controller 31 and is known to thestylus 100 in advance (before the stylus 100 detects the sensorcontroller 31). The symbol here means the unit of a value, which isconverted by the direct spreading circuit 63 into a spreading codesequence. The symbol includes a value converted by the stylus 100, whichhas received a symbol, into a bit string (hereinafter referred to as a“bit string associated symbol”) and a value not converted by the stylus100, which has received a symbol, into a bit string (hereinafterreferred to as a “bit string nonassociated symbol”). A symbol pertainingto the former is denoted as the bit string itself after the conversionsuch as “0” or “0001.” The bit length of each symbol denoted by a bitstring described above is determined by the specification of the directspreading circuit 63. On the other hand, a symbol pertaining to thelatter (bit string nonassociated symbol) is denoted as “P,” “M,” and soon. As an example, “P” and “M” are associated with a spreading codesequence and an inverted code sequence thereof, respectively.

A specific example of the detection pattern c1 will be given below. Forexample, the detection pattern c1 can be expressed by a bit stringassociated symbol pattern having a bit length 1, and in this case, thedetection pattern c1 can be made up, for example, of “010101 . . . .”Also, the detection pattern c1 can be expressed by a bit stringassociated symbol pattern having a bit length 4, and in this case, thedetection pattern c1 can be made up, for example, of “0000, 1000, 0000,1000, . . . .” Further, when the detection pattern c1 is expressed by abit string nonassociated symbol pattern, the detection pattern c1 can bemade up, for example, of “PMPMPM . . . .” In any case, it is preferredthat the detection pattern c1 be a symbol pattern made up of alternatelyrepeating symbol values different from each other.

The end pattern STP is a symbol pattern for notifying the stylus 100 ofthe end of the continuous transmission period and is made up of a symbolpattern that does not appear in the repeated detection pattern c1. Forexample, if the detection pattern c1 is made up of “PMPMPM . . . ” asdescried above, the end pattern STP can be made up of a symbol pattern“PP” which is two consecutive occurrences of “P,” which is a bit stringnonassociated symbol.

The switch 62 has a function to select one of the first control signalsupply circuit 61 and the MCU 80 based on a control signal ctrl t2supplied from the logic circuit 70 and supply the selected one of theoutputs to the direct spreading circuit 63. If the switch 62 selects thefirst control signal supply circuit 61, the direct spreading circuit 63is supplied with the above detection pattern c1 or the end pattern STP.On the other hand, if the switch 62 selects the MCU 80, the directspreading circuit 63 is supplied with control information c2.

The control information c2 is information that includes a commandindicating details of an instruction issued to the stylus 100 and isgenerated by the MCU 80. The control information c2 is information thatforms a command for requesting the capability information CP from thestylus 100 or a command for setting a transmission method of the data D.The control information c2 includes a plurality of bits (arbitrary bitstring) whose value is not shared with the stylus 100 in advance.

The spreading code holding circuit 64 has a function to generate aspreading code having autocorrelation based on a control signal ctrl t3supplied from the logic circuit 70. The spreading code generated by thespreading code holding circuit 64 is supplied to the direct spreadingcircuit 63.

The direct spreading circuit 63 generates the beacon signal BS byconverting the signals (detection pattern c1, end pattern STP, andcontrol information c2, in various embodiments) supplied from the switch62 using the spreading code supplied from the spreading code holdingcircuit 64.

As a specific example, if, for example, the detection pattern c1, theend pattern STP, and the control information c2 are made up ofcombinations of “0s” and “1s,” which are bit string associated symbols,and if the spreading code supplied from the spreading code holdingcircuit 64 is “00010010111,” the direct spreading circuit 63 generates,as illustrated in Table 1, the beacon signal BS by converting the symbol“0” into a spreading code “00010010111” and the symbol “1” into aninverted code “11101101000” of the spreading code “00010010111.”

TABLE 1 Spreading Code After Symbol Conversion 0 00010010111 111101101000

Also, for example, if the detection pattern c1, the end pattern STP, andthe control information c2 are made up of combinations of bit stringassociated symbols “0000” to “1111” and bit string nonassociated symbols“P” and “M,” and if the spreading code supplied from the spreading codeholding circuit 64 is “00010010111,” the direct spreading circuit 63generates the beacon signal BS by converting the bit stringnonassociated symbol “P” into a code string made up of “1” followed by“00010010111,” converting the bit string nonassociated symbol “M” into acode string made up of “0” followed by the inverted code “11101101000”of “00010010111,” converting each of the bit string associated symbols“0000” to “0100” into a code string made up of “1” followed by the codeobtained by cyclically shifting “00010010111” by a given shift amount,and converting each of the bit string associated symbols “1000” to“1100” into a code string made up of “0” followed by the code obtainedby cyclically shifting the inverted code “11101101000” of “00010010111”by a given shift amount, as illustrated in Table 2.

TABLE 2 Spreading Spreading Code After Code After Symbol ConversionSymbol Conversion P 100010010111 M 011101101000 0000 111000100101 1000000111011010 0001 111100010010 1001 000011101101 0011 101110001001 1011010001110110 0010 110111000100 1010 001000111011 0110 101011100010 1110010100011101 0111 100101110001 1111 011010001110 0101 110010111000 1101001101000111 0100 101001011100 1100 010110100011

It should be noted that the beacon signal BS generated by the directspreading circuit 63 is a signal that includes the detection pattern c1,the end pattern STP, and the control information c2 in this order.

The transmitting guard circuit 65 is a functional circuit that inserts aguard period, which is a period during which neither transmission norreception is conducted to switch between transmission and receptionoperations, at the end of a transmission period of the beacon signal BS(time slot s0 depicted in FIG. 2) based on a control signal ctrl t4supplied from the logic circuit 70. In FIG. 2, the blank portion betweenthe end of the beacon signal BS and the end of the time slot s0 is thisguard period.

The selecting circuit 40 is a switch that switches between thetransmission period during which signals are sent from the sensor 30 andthe reception period during which signals are received by the sensor 30based on control performed by the logic circuit 70. Describingspecifically, the selecting circuit 40 is configured to include a switch44 x and a switch 44 y and a conductor selection circuit 41 x and aconductor selection circuit 41 y. The switch 44 x operates, based on acontrol signal sTRx supplied from the logic circuit 70, in such a manneras to connect the output end of the transmitting circuit 60 to the inputend of the conductor selection circuit 41 x during the transmissionperiod and connect the output end of the conductor selection circuit 41x to the input end of the receiving circuit 50 during the receptionperiod. The switch 44 y operates, based on a control signal sTRysupplied from the logic circuit 70, in such a manner as to connect theoutput end of the transmitting circuit 60 to the input end of theconductor selection circuit 41 y during the transmission period andconnect the output end of the conductor selection circuit 41 y to theinput end of the receiving circuit 50 during the reception period. Theconductor selection circuit 41 x operates, based on a control signalselX supplied from the logic circuit 70, in such a manner as to selectone of the plurality of linear electrodes 30X and connect the selectedelectrode to the switch 44 x. The conductor selection circuit 41 yoperates, based on a control signal selY supplied from the logic circuit70, in such a manner as to select one of the plurality of linearelectrodes 30Y and connect the selected electrode to the switch 44 y.

The receiving circuit 50 is a circuit that receives the downlink signalDS sent by the stylus 100 based on a control signal ctrl_r of the logiccircuit 70. Specifically, the receiving circuit 50 is configured toinclude an amplifying circuit 51, a detecting circuit 52, and ananalog-digital (AD) converter 53.

The amplifying circuit 51 amplifies the downlink signal DS supplied fromthe selecting circuit 40 and outputs the amplified signal. The detectingcircuit 52 is a circuit that generates a voltage proportional to thelevel of the output signal of the amplifying circuit 51. The ADconverter 53 is a circuit that generates digital data by sampling thevoltage output from the detecting circuit 52 at given time intervals.Digital data output from the AD converter 53 is supplied to the MCU 80.

The MCU 80 is a microprocessor that incorporates a read only memory(ROM) and a random access memory (RAM) and operates based on a givenprogram. The logic circuit 70 outputs various control signals describedabove based on control performed by the MCU 80. The MCU 80 also takescharge of deriving coordinate data (X,Y) indicating the position of thestylus 100 and other data based on digital data supplied from the ADconverter 53 and outputting such data to the system controller 32.

In various embodiments, several drawing and signature verificationalgorithms that may run on the system controller 32 are implementedbased on the premise that the data D such as position information (X,Y)and the pen pressure value TiP supplied from the sensor controller 31 isobtained at regular intervals on the time axis. Therefore, if there is acase in which the interactive data DF cannot be sent (i.e., the data Dstutters) in a time slot, where the interactive data DF should be sentunder normal circumstances, because of occasional transmission of thenoninteractive data DINF, it is likely that the above drawing andsignature verification algorithms may not work properly. For thisreason, the time slot used for transmission of the noninteractive dataDINF should be selected not to interfere with communication of theinteractive data DF at regular intervals. Details of such configurationwill be described later with reference to FIG. 18 and FIG. 19.

Also, there is a possibility that the capability information CP maychange while the stylus 100 is located outside the sensing range SR ofthe sensor controller 31 as described earlier. For an inking process(process for adding information such as color information and line widthto the coordinate data sequence) to be performed in the systemcontroller 32, which is the host of the sensor controller 31, it isnecessary that the sensor controller 31 has the capability informationCP (e.g., the color Col and the style Styl that specifies the line widthand brush type depicted in FIG. 8 in particular). Similarly, when theMCU 80 derives coordinate data (X,Y) and so on indicating the positionof the stylus 100, it is necessary that the refill body type ID includedin the capability information CP be known to the sensor controller 31.For this reason, the capability information CP always becomes known tothe sensor controller 31 anew each time the stylus 100 enters thesensing range SR. Specifically, the capability information CP is sent tothe sensor controller 31 as a response signal to the beacon signal BSbefore the data D (interactive data DF) is sent from the stylus 100 tothe sensor controller 31. Details of such configuration will bedescribed later with reference to FIG. 16 and FIG. 17.

FIG. 8 is a diagram illustrating a configuration of the capabilityinformation CP. As depicted in the same figure, the capabilityinformation CP is a set of a plurality of pieces of individualcapability information that are assigned different “Information Names.”Each piece of individual capability information is contained in thecapability information CP with the bit length indicated in “TransmissionSize” when the capability information CP is sent. Also, some pieces ofindividual capability information are essential (Y) and must becontained in the capability information CP while others are notessential (N) in various embodiments. An example of the distinctionbetween (Y) and (N) is illustrated to indicate typical examples of thenumber of bits required to form the capability information CP.

Pieces of individual capability information constituting the capabilityinformation CP may specifically include a vendor identifier VID, aserial number SN, the color Col, the style Styl, a state of the tailswitch 103, a version Ver, the refill body type ID, and a data formatDFmt as depicted in FIG. 8.

The vendor identifier VID is 8-bit information indicating the vendor ofthe stylus 100. The serial number SN is 56-bit information unique toeach vendor assigned by each vendor. Adding the vendor identifier VID tothe serial number SN generates a 64-bit unique user identifier UID(unique ID of the stylus 100).

The color Col is information representing 140 colors with 8 bits, whichcan be used in cascading style sheets (CSS), and is changed by operationof the tail switch 103.

The style Styl is 3-bit information that specifies the effect of theinking process by identifying, for example, whether the pen tip of thestylus 100 is a brush or a ballpoint pen.

The state of the tail switch 103 is information indicating the ON/OFFoperating state of the tail switch 103. Although it is a piece ofindividual capability information among the capability information CP,this information is reflected in changes made to other individualcapability information. As a result, it is not necessary to notify theinformation itself to the sensor controller 31. Therefore, thetransmission size of the state of the tail switch 103 is set as “notapplicable (N/A).”

The version Ver is 4-bit information indicating the version of thecommunication protocol used by the stylus 100.

The refill body type ID is information indicating the type of the refillbody 121 attached to the stylus 100 and obtained by the capabilityinformation updating circuitry 111 depicted in FIG. 4 as described withreference to FIG. 5 and FIG. 6. The sensor controller 31 obtains, byreferring to the refill body type ID, information on the electrode 102including whether the electrode 102 used by the stylus 100 for signaltransmission is located inside or outside the refill body 121, thenumber of such electrodes 102, and the arrangement thereof. It should benoted that the refill body type ID may be part of the unique ID of thestylus 100 described above.

The data format DFmt is typically 10- to 44-bit information thatidentifies the format of data signals used to send the data D (e.g.,interactive data DF). Details of the data format DFmt will be describedlater with reference to FIG. 9.

As described above, the capability information CP includes variouspieces of individual capability information, and of these, essentialpieces of information (Y) that must be contained in the capabilityinformation CP (user identifier UID and data format DFmt) alone have alarge transmission size in excess of 70 bits, for example. Therefore,when the number of bits that can be sent in one time slot is 16 bits asdescribed above, it may not be possible to complete the transmission ofthe entire capability information CP within one time slot.

FIG. 9 is a diagram illustrating details of the data format DFmtdepicted in FIG. 8. As illustrated in the same figure, the data formatDFmt is a set of a plurality of individual formats that are assigneddifferent “Names.” Each individual format is contained in the dataformat DFmt with the bit length indicated in “Transmission Size” whenthe capability information CP is determined and sent.

Individual formats forming the data format DFmt specifically include anumber of pen pressure reading levels PL, a number of barrel buttonsBBN, a tangential pen pressure flag TaPf, the orientation code ORC, acustom data flag CDf, an orientation resolution ORR, a custom penpressure size CPS, a custom button size CBS, a custom orientation sizeCOS, and a custom data size CDS. The meaning of each is given in the“Definition” column in FIG. 9. These details indicate the types of oneor more individual pieces of interactive data (described later) that canbe obtained by the stylus 100 and their transmission sizes. They aredetermined based on the one or more pieces of interactive data that canbe obtained by the stylus 100 in steps S1 and S3 of FIG. 14 which willbe described later. Each will be described in detail below.

The number of pen pressure reading levels PL is 3-bit informationindicating the number of levels (resolution) of the pen pressure valueTiP (refer to FIG. 12), which is one of the interactive data DF. Whenthe value PL is any one of 0 to 6, this indicates that the number oflevels is 256×2^(PL). In the case of PL=0, which is considered identicalto PL=−8, the number of pen pressure levels is 256×2°=256. When PL=7,the number of pen pressure levels is uniquely specified as a custom penpressure size CPS.

The number of barrel buttons BBN is 2-bit information indicating thenumber of barrel buttons 104 (refer to FIG. 3) available with the stylus100. When the value BBN is any one of 0 to 2, the number indicates thenumber of barrel button(s) 104 included in the stylus 100. If the stylus100 has operating elements other than the barrel buttons 104, the numberthereof may also be added to the number of barrel buttons BBN. WhenBBN=3, is indicates a custom number (custom button size) CBS ofoperating elements including the barrel buttons 104. The number ofbarrel buttons BBN may be bits that respectively represent the presenceor absence of the first barrel button to the BBNth barrel button. Forexample, if there are two bits, each of these bits may indicate whetherthe first barrel button is provided or whether the second barrel buttonis provided.

The tangential pen pressure flag TaPf is 1-bit information indicatingwhether or not the stylus 100 is capable of obtaining a tangential penpressure value (pressure applied in the direction tangential to thetouch surface 3 a), and indicates that when the flag is 0, the stylus100 is not capable, and that when the flag is 1, the stylus 100 iscapable. The same number of levels as the number of pen pressure readinglevels PL is used as the number of levels when the stylus 100 is capableof obtaining a tangential pen pressure.

The orientation code ORC is 3-bit information that specifies the formatof the orientation OR (refer to FIG. 12), which is one of theinteractive data DF. Although the orientation code ORC will be describedin detail later with reference to FIG. 10, when ORC=7, only the datasize of the orientation OR is specified as a custom orientation sizeCOS.

The custom data flag CDf is 1-bit information that indicates whether ornot the stylus 100 acquires custom data CD (vendor's unique data notstandardized as one of the interactive data DF; refer to FIG. 12) andindicates that when the flag is 0, the custom data CD does not exist,and that when the flag is 1, the custom data CD exists.

The orientation resolution ORR is 0- to 2-bit information that indicatesthe resolution of the orientation OR (refer to FIG. 12) and is containedin the data format DFmt when the value of the orientation code ORC isgreater than 0, that is, only when the stylus 100 is capable ofobtaining the orientation OR. The resolution of the orientation ORindicated by the orientation resolution ORR is (8+ORR) bits.

The custom pen pressure size CPS is 8-bit information indicating acustom value of pen pressure levels and is contained in the data formatDFmt only when the number of pen pressure reading levels PL is 7.Because the custom pen pressure size CPS is 8 bits, the maximum numberof pen pressure levels that can be represented by the custom penpressure size CPS is 256.

The custom button size CBS is 8-bit information indicating the number ofoperating elements including the barrel buttons 104 and is contained inthe data format DFmt only when the number of barrel buttons BBN is 3.Because the custom button size CBS is 8 bits, the maximum number ofoperating elements that can be represented by the custom button size CBSis 256.

The custom orientation size COS is 8-bit information that indicates thenumber of bytes of the orientation OR and is contained in the dataformat DFmt only when the orientation code ORC is 7. Because the customorientation size COS is 8 bits, the maximum number of bytes of theorientation OR that can be represented by the custom orientation sizeCOS is 256 bytes. It should be noted, however, that the actual maximumsize of the orientation OR is 72 bits, as will be described later withreference to FIG. 12.

The custom data size CDS is 8-bit information that indicates the numberof bytes of the custom data CD and is contained in the data format DFmtonly when the custom data flag CDf is 1. Because the custom data sizeCDS is 8 bits, the maximum number of bytes of the custom data CD thatcan be represented by the custom data size CDS is 256 bytes. As will bedescribed later with reference to FIG. 12, the actual maximum size ofthe custom data CD is 256 bits.

As has been described up to this point, in the system 1, each of thedata sizes of the custom values indicated respectively by the custom penpressure size CPS, the custom button size CBS, the custom orientationsize COS, and the custom data size CDS is 8 bits when the size iscontained in the data format DFmt and 0 bit when the size is notcontained in the data format DFmt. This is a configuration thateliminates the need for a bit that indicates the end position, while atthe same time achieving the data format DFmt having a variable length,and facilitates simplification of the data format DFmt as a result.

FIG. 10 is a diagram illustrating a definition of the orientation codeORC (orientation code table OCT) depicted in FIG. 9. In the same figure,“ORC” at the left end indicates the value of the orientation code ORC,and “Data Size” at the right end indicates the data size of theorientation OR with a number of exclusively used time slots (number oftime slots required to send the orientation OR once).

That the value of the orientation code ORC is “0” indicates that thestylus 100 does not obtain the orientation OR (or does not have afunction to obtain the orientation OR). As illustrated in FIG. 21 whichwill be described later, when the orientation OR is contained in theinteractive data DF, it is necessary to have additional time slotsavailable for sending the interactive data DF. However, when the valueof the orientation code ORC is “0,” such additional time slots are notnecessary.

That the value of the orientation code ORC is “1” indicates that thestylus 100 can obtain the orientation OR indicating a two-dimensional(2D) inclination with two directional values (X tilt, Y tilt) and thattwo time slots are required to send that orientation OR once. Although,in the example of FIG. 21 which will be described later, two consecutivetime slots are assigned for transmission of the orientation OR, the twotime slots may be consecutive or not consecutive.

That the value of the orientation code ORC is “2” indicates that thestylus 100 can obtain the orientation OR indicating a three-dimensional(3D) value made up of a two-dimensional (2D) inclination with twodirectional values (X tilt, Y tilt) and a twist, which is an amount ofrotation around a pen axis, and that three consecutive or inconsecutivetime slots are required to send that orientation OR once.

That the value of the orientation code ORC is “3” indicates that thestylus 100 can obtain the orientation OR indicating a two-dimensional(2D) inclination with two directional values (altitude, azimuth) andthat two time slots are required to send that orientation OR once.

That the value of the orientation code ORC is “4” indicates that thestylus 100 can obtain the orientation OR indicating a three-dimensional(3D) value made up of a two-dimensional (2D) inclination with twodirectional values (altitude, azimuth) and a twist, which is an amountof rotation around the pen axis, and that three time slots are requiredto send that orientation OR once.

That the value of the orientation code ORC is “5” indicates that thestylus 100 can obtain the orientation OR, which is a measured value of a6-axis IMU including accelerometer and gyro, and that three time slotsare required to send that orientation OR once.

That the value of the orientation code ORC is “6” indicates that thestylus 100 can obtain the orientation OR, which is a measured value of a9-axis IMU, and that three time slots or more are required to send thatorientation OR once.

That the value of the orientation code ORC is “7” indicates, asdescribed earlier, that the number of bytes of the orientation OR isrepresented by the custom orientation size COS illustrated in FIG. 9.

As described above, the use of the orientation code ORC makes itpossible to notify, to the sensor controller 31, the presence or absenceof orientation detection functions of the stylus 100 or the type of theorientation OR that can serve as various information in accordance withthe type of the IMU, using 3-bit short information. It is also possibleto notify, to the sensor controller 31, the number of time slotsrequired in relation to the use of the different number of consecutiveor inconsecutive time slots in accordance with the type of theorientation OR.

FIG. 11 depicts diagrams illustrating description examples of the dataformat DFmt depicted in FIG. 8. Description example 1 illustrated inFIG. 11(a) and description example 2 illustrated in FIG. 11(b) depictcases in which the data format DFmt is represented by 9 bits, with nocustom value included (i.e., exclusive of the “NO CUSTOM DATA” flag bit1). In description example 1, the value of the orientation code ORC is 0(0b000), that is, the stylus 100 does not obtain the orientation OR.Therefore, it is not necessary to have additional time slots for theorientation OR. In description example 2, on the other hand, the valueof the orientation code ORC is 6 (0b110). Therefore, it is necessary tohave three additional time slots or more for the orientation OR. Also,description example 3 illustrated in FIG. 11(c) depicts a case in whichthe number of pen pressure reading levels PL is customized andrepresented by the custom pen pressure size CPS. In this case, the 8-bitcustom pen pressure size CPS is described at the end of the data formatDFmt. As a result, the number of bits of the data format DFmt is 17.

As described above, the data format DFmt included in the capabilityinformation CP according to the present embodiment is represented by abit string of 10 bits to 44 bits (see FIG. 9). Because the data formatDFmt is notified from the stylus 100 to the sensor controller 31, thesensor controller 31 becomes aware of the elements of the interactivedata DF, the size, and the presence or absence of optional data beforeit receives the interactive data DF. Thereafter the interactive data DFis sent from the stylus 100.

FIG. 12 is a diagram illustrating a configuration of the interactivedata DF. As illustrated in the same figure, the interactive data DF is aset of a plurality of pieces of individual interactive data that areassigned different “Names.” Each piece of individual interactive data iscontained in the interactive data DF with the bit length indicated in“Transmission Size” when the interactive data DF is sent. Also, somepieces of individual interactive data are essential (Y) and must becontained in the interactive data DF while others are not essential (N).In the figure, an example of the distinction between (Y) and

(N) is illustrated to count the total number of bits typically requiredto form the interactive data DF. The order of transmission of individualinteractive data is also depicted in the same figure, and the stylus 100is configured to send the individual interactive data in the order fromthe top to the bottom in the figure.

Individual interactive data forming the interactive data DF specificallyincludes the pen pressure value TiP, a tangential pen pressure valueTaP, the barrel button state BB, an inversion Inv, the orientation OR,and the custom data CD.

The pen pressure value TiP is 8- to 256-bit information that indicatesthe pen pressure value applied to the distal tip of the stylus 100 andis detected by the operation state detection circuitry 105 depicted inFIG. 3. The pen pressure value TiP is always contained in theinteractive data DF (Y). The number of bits of the pen pressure valueTiP is derived from the number of pen pressure reading levels PL or thecustom pen pressure size CPS in the data format DFmt illustrated in FIG.9. For example, when the number of pen pressure reading levels PL is 0(or −8), the number of pen pressure levels is 256. As a result, thenumber of bits of the pen pressure value TiP is log₂256=8. In a typicalexample, the number of bits of the pen pressure value TiP is 8 (256levels) to 11 (2048 levels).

The tangential pen pressure value TaP is 0- to 256-bit information thatindicates the tangential pen pressure value and is detected by theoperation state detection circuitry 105 depicted in FIG. 3. Thetangential pen pressure value TaP is optional data and is contained inthe interactive data DF only when the tangential pen pressure flag TaPfdepicted in FIG. 9 is 1 (N). The number of bits of the tangential penpressure value TaP when the tangential pen pressure value TaP iscontained in the interactive data DF is the same as that for the penpressure value TiP. In a typical example, the tangential pen pressurevalue TaP is 0-bit information and is not contained in the interactivedata DF.

The barrel button state BB is 2- to 256-bit information that indicatesthe pressed state of the barrel button 104 depicted in FIG. 3. Thebarrel button state BB is always contained in the interactive data DF(Y) in the illustrated embodiment. The number of bits of the barrelbutton state BB is a value equal to the number of barrel buttons 104indicated by the number of barrel buttons BBN, or the custom button sizeCBS in the data format DFmt illustrated in FIG. 9. For example, when thenumber of barrel buttons BBN is 1, the number of barrel buttons 104included in the stylus 100 is 2. As a result, the number of bits of thebarrel button state BB is 2. In a typical example, the number of bits ofthe barrel button state BB is 2.

The inversion Inv is 1-bit information and contained in the interactivedata DF (Y).

The orientation OR is 0- to 72-bit data that indicates the orientationof the stylus 100 and is detected by the operation state detectioncircuitry 105 depicted in FIG. 3. The orientation OR is optional dataand contained in the interactive data DF only when the orientation codeORC depicted in FIG. 9 is not 0 (refer to FIG. 10) (N). The specificmeaning of the orientation OR is represented by the orientation code ORCas described with reference to FIG. 10. On the other hand, the size ofthe orientation OR is indicated by the data size illustrated in FIG. 10(including the case in which the size is specified by the customorientation size COS). For example, the orientation OR representing atwo-dimensional or three-dimensional value is sent by using two timeslots or three time slots in accordance with the specification in theorientation code table OCT depicted in FIG. 10 (refer to FIG. 21).

The custom data CD is 0- to 256-bit information uniquely specified bythe vendor of the stylus 100. The custom data CD is optional data andcontained in the interactive data DF only when the custom data flag CDfdepicted in FIG. 9 is 1 (N). The number of bits of the custom data CD isrepresented by the custom data size CDS depicted in FIG. 9. For example,when the custom data size CDS is 1, the number of bytes of the customdata CD is 1. As a result, the number of bits of the custom data CD is8.

The number of bits of the interactive data DF is, in an example of aminimum number, 11 bits which is the total of the 8-bit pen pressurevalue TiP, the 2-bit barrel button state BB, and the 1-bit inversion Inv(15 bits when a 4-bit error detection code is added). Also, in a typicalexample, the number of bits which is the total of the 11-bit penpressure value TiP, the 2-bit barrel button state BB, and the 1-bitinversion Inv amounts to 14 bits (18 bits when a 4-bit error detectioncode is added). As described above, it is possible to send 16 bits worthof data per time slot. Therefore, the transmission of the interactivedata DF not including the orientation OR nor the custom data CD can becompleted in one time slot (refer to FIG. 18 and FIG. 19). On the otherhand, the transmission of the interactive data DF including theorientation OR or the custom data CD normally exceeds 16 bits and,therefore, cannot be completed in one time slot, resulting in use of aplurality of time slots (refer to FIG. 20 and FIG. 21).

FIG. 13 is a diagram illustrating a configuration of the noninteractivedata DINF. As illustrated in the same figure, the noninteractive dataDINF is a set of a plurality of pieces of individual noninteractive datathat are assigned different “Names.” Each piece of individualnoninteractive data is contained in the noninteractive data DINF withthe bit length indicated in “Transmission Size” when the noninteractivedata DINF is sent.

Only the battery level BL is depicted in FIG. 13 as an example ofindividual noninteractive data forming the noninteractive data DINF. Thebattery level BL is 4-bit information indicating the remaining capacitylevel of the battery 101 depicted in FIG. 3. It is a matter of coursethat other kinds of individual noninteractive data may be included inthe noninteractive data DINF.

The noninteractive data DINF is sent once every plurality of frames F(e.g., every several hundred frames) as described above (refer to FIG.18 to FIG. 21).

A detailed description will be given of the operation of the stylus 100and the sensor controller 31 with reference to FIG. 14 to FIG. 21.

First, FIG. 14 is a diagram illustrating a flow of operation of thestylus 100.

The stylus 100 proceeds with the operation, to be described in section“A1” below, while it is located outside the sensing range SR after poweris turned on.

<A1. Updating Process of the Capability Information CP (OperationOutside the Sensing Range SR)>

The stylus 100 determines the capability information CP including thedata format DFmt after power is turned on (step S1). At this time, thestylus 100 obtains the refill body type ID from the potential levelsupplied to the terminals D1 and D0 depicted in FIG. 3. The stylus 100also determines details of the data format DFmt based on the one or morepieces of the interactive data DF that can be obtained by the stylus 100itself. That is, when, for example, the stylus 100 is capable ofobtaining a tangential pen pressure as described above, the tangentialpen pressure flag TaPf in the data format DFmt is 1, and when the stylus100 is not capable of obtaining a tangential pen pressure, thetangential pen pressure flag TaPf in the data format DFmt is 0.Thereafter, the stylus 100 determines whether the user has performed anyoperation to change the capability information CP (specifically,replacement of the refill body 121 or operation of the tail switch 103)(step S2). Then, when an operation has been performed to change thecapability information CP, the capability information CP determined instep S1 is changed to correspond with the nature of the operation (stepS3).

After the processes in step S2 and step S3, the stylus 100 determineswhether the beacon signal BS has been detected (step S4). This step S4is intended to determine whether the pen lowering operation C1 describedwith reference to FIG. 1 has been performed, and the stylus 100according to the present embodiment sends the capability information CPincluding the refill body type ID by using detection of this beaconsignal BS as a trigger (a trigger that occurs when the pen loweringoperation takes place) (step S6 to step S8 described later). Whendetermining in step S4 that the beacon signal BS has not been detected(i.e., the stylus 100 is located outside the sensing range SR of thesensor controller 31), the stylus 100 will return to step S2 to repeatthe processes up to this point. On the other hand, when determining instep S4 that the beacon signal BS has been detected, the stylus 100 willproceed with the operation described in section “A2” below.

<A2. Operation after the Stylus 100 Enters the Sensing Range SR>

After entering the sensing range SR of the sensor controller 31 as aresult of the pen lowering operation C1 of the user (affirmativedetermination in step S4), the stylus 100 synchronizes with the frame Fspecified by the sensor controller 31 with reference to the detectedbeacon signal BS and identifies (determines) the time slots s0 to s15thereof (step S5).

<A2-1. Communication of the Capability Information CP>

Next, the stylus 100 performs a process of rendering the capabilityinformation CP known to the sensor controller 31 (sharing the capabilityinformation CP with the sensor controller 31) (step S6 to step S8).Here, in the system 1, the number of bits that can be sent in one timeslot is limited, for example, to 16 bits as described above. On theother hand, the capability information CP is information that exceeds 70bits as described above. Therefore, all the capability information CPcannot be sent in one time slot. As a result, it is necessary to sendthe capability information CP in batches over a plurality of time slotsif all the information is sent. However, if such transmission in batchesis conducted not just once, but twice and three times, there is alikelihood that the transmission of the capability information CP maynot be completed by the time the stylus 100 comes in contact with thetouch surface 3 a (refer to FIG. 1) and that, as a result, an unpleasantcondition for the user may occur, which is that, despite the fact thatthe stylus 100 is in contact with the touch surface 3 a, a line is notdrawn. In the present embodiment, therefore, information equivalent tothe capability information CP (specifically, hash value of thecapability information CP) rather than the capability information CPitself is sent to the sensor controller 31, to which all the capabilityinformation CP has already been sent once. A specific description willbe given below.

The stylus 100 determines first whether the stylus 100 has already beenpaired with the sensor controller 31 that sends out the beacon signal BS(step S6). This determination can be made, for example, by determiningthe register value in the stylus 100. It should be noted that, invarious embodiments, the beacon signal BS does not include anyinformation that identifies the sensor controller 31. Therefore, thedetermination here is about whether the stylus 100 has been paired with(any) one of the sensor controllers 31 and is not about whether thestylus 100 has been paired with the specific sensor controller 31.

When determining that the stylus 100 has yet to be paired with thesensor controller 31 as a result of the determination in step S6(negative determination in step S6), the stylus 100 will repeatedly sendthe capability information CP (information exceeding 70 bits depicted inFIG. 8; including the data format DFmt and the user identifier UID madeup of the serial number SN and the vendor identifier VID) in a pluralityof time slots (step S7).

FIG. 16 is a diagram illustrating an example of allocation of time slotsto the capability information CP. The stylus 100 in the example depictedin the same figure divides the capability information CP into aplurality of pieces of partial capability information CP1, CP2 and so onand sends them in the time slots s1 of frames Fn, Fn+1 and so on,respectively. Thus, the transmission of the capability information CPrequires a plurality of time slots worth of time (a plurality of framesworth of time in this example). This is a process that is required atleast once at first. It should be noted that the capability informationCP needs to be sent using the time slot s1 as also depicted in FIG. 16.The reason for this is to ensure transmission of the capabilityinformation CP or shortened information (hash value CP_Hash) at a timewhen a response signal to the beacon signal BS including a commandshould be sent. This way, the sensor controller 31 can recognize thepresence or absence of a response signal (the presence or absence of thestylus 100) to the beacon signal BS by monitoring the signal received inthe time slot s1 following the transmission of the beacon signal BS, andtime slots s2 to s15 that follow the time slot s1 can be reserved forreception of the data D.

On the other hand, when determining that the stylus 100 has already beenpaired with the sensor controller 31 as a result of the determination instep S6 (affirmative determination in step S6), the stylus 100 will sendminimum information for identifying the capability information CP, whichis a piece of information of a size that can be sent in one time slot(shortened information) using one time slot s1 rather than sending allthe capability information CP including the data format DFmt in step S7(step S8). It is preferred that this information should, for example, beinformation that permits identification, with a given probability, ofwhether or not the associated capability information CP is authentic,such as the hash value CP_Hash of 20 bits or less (e.g., 16 bits) of thecapability information CP. In the description given below, it is assumedthat the hash value CP_Hash is used as shortened information. Whensending the hash value CP_Hash in step S8, the stylus 100 will perform aprocess of deriving the hash value CP_Hash from the capabilityinformation CP prior to the transmission.

FIG. 17 is a diagram illustrating an example of allocation of timeslot(s) to the hash value CP_Hash of the capability information CP. Asillustrated in the same figure, the transmission of the hash valueCP_Hash is completed only in the time slot s1 of the frame Fn. As aresult, the interactive data DF can be sent in the time slot s1 from thenext frame Fn+1.

Thus, in the system 1 according to the present embodiment, after thecapability information CP becomes known to the sensor controller 31 once(after the stylus 100 is paired with the sensor controller 31), eachtime the stylus 100 enters the sensing range SR, the stylus 100 cannotify the sensor controller 31 of the capability information CP(including the data format DFmt) by sending shortened information(specifically, the hash value CP_Hash) in place of sending thecapability information CP at has already been sent once. It is possiblefor the sensor controller 31 to identify the capability information CPof the approaching stylus 100 with a probability that does notsubstantially cause any practical problem by simply receiving shortenedinformation in one time slot.

It should be noted that although, in the present embodiment, adescription has been given assuming that the sensor controller 31unconditionally accepts the capability information CP sent by the stylus100, the sensor controller 31 may determine that part or whole ofinformation specified in the capability information CP is not acceptedin accordance with its own resources and notify details of thedetermination to the stylus 100. In this case, the stylus 100 does notsend information that is not accepted by the sensor controller 31.Details in this regard will be described later with reference to FIG.22.

<A2-2. Communication of the Data D>

After the transmission of the capability information CP or the hashvalue CP_Hash is completed, the stylus 100 sends a data signal includingthe data D (step S10 to step S15). Specifically, the stylus 100 detectsthe beacon signal BS (step S10).

After detecting the beacon signal BS in step S10 (affirmativedetermination in step S10), the stylus 100 resets a consecutivenon-detection counter to 0 (step S11). Then, the stylus 100 sends a datasignal including the interactive data DF in the format (typically 11 to14 bits) specified in the data format DFmt of the capability informationCP at least once per frame F (step S12).

It should be noted that although, in the present embodiment, adescription will be given assuming that the stylus 100 decides on thetime slot to be used for transmission of the data D, the sensorcontroller 31 may decide on the time slot to be used for transmission ofthe data D and notify the details of the decision to the stylus 100.Details in this regard will be described later with reference to FIG.22.

FIG. 18 is a diagram illustrating an example of allocation of time slotsto the interactive data DF and the noninteractive data DINF. In theexample depicted in the same figure, the 14-bit interactive data DF,which is a piece of interactive data having a typical size, is sentusing four time slots s2, s6, s10, and s14 per frame F (data signalsDF1, DF2, DF3, and DF4). In these four time slots s2, s6, s10, and s14,the interactive data DF is sent one piece at a time. According to theallocation of time slots according to this example, as illustrated inFIG. 18, not only within each individual frame F but also acrossmultiple frames F, the interval between the time slots used fortransmission of the interactive data DF is maintained (the intervalbetween the data signal DF4 (time slot s14) sent last in the frame Fn+1and a data signal DF5 (time slot s2) sent first in a next frame Fn+2 isthree time slots which is the same as that within the individual frameF). This makes it possible to send the interactive data DF periodicallyat the fixed period T (=four time slots). Such a feature of the system 1is preferred for an application of the system controller 32 thatrequires the acquisition of the interactive data DF at regularintervals.

It should be noted that the value having the period T of four time slotsdepicted in FIG. 18 is the shortest under the condition in which thetime slots s0 and s1 (and a time slot s15 which will be described later)are reserved (i.e., under the condition in which the time slot s0 isreserved for transmission of the beacon signal BS, the time slot s1 isreserved for transmission of a response signal to the beacon signal BS,and the time slot s15 is reserved for transmission of the noninteractivedata DINF). Setting the period T to be the shortest value allows forimprovement of the number of transmissions of the interactive data DF.It is also possible for the sensor controller 31 to obtain more detailedcoordinate data of the stylus 100.

FIG. 19 is a diagram illustrating another example of allocation of timeslots to the interactive data DF and the noninteractive data DINF. Inthe example depicted in the same figure, the 14-bit interactive data DF,which is a piece of interactive data having a typical size, is sentusing four time slots s3, s7, s11, and s15 per frame F (data signalsDF1, DF2, DF3, and DF4). Such allocation of time slots also allows forperiodic transmission of the interactive data DF at the shortest periodT (=four time slots) as in the example depicted in FIG. 18.

Referring back to FIG. 14, the stylus 100 sends the noninteractive dataDINF at a rate of once every plurality of frames F (once every severalhundred frames F) (step S13). It should be noted that, as describedabove, the stylus 100 may send the noninteractive data DINF in responseto polling (request to send) from the sensor controller 31. In thiscase, polling from the sensor controller 31 is contained in the beaconsignal BS as a command.

Referring again to FIG. 18, the noninteractive data DINF is sent in thetime slot s15 in this example. In the example depicted in FIG. 18, thetime slot s15 is usually not used. However, such a time slot s15 is usedto send the noninteractive data DINF once every plurality of frames F,making it possible to send the noninteractive data DINF withoutaffecting the transmission period T of the interactive data DF.

In the example depicted in FIG. 19, on the other hand, thenoninteractive data DINF is sent in the time slot s1. The time slot s1is originally used to send a response signal (capability information CPand hash value CP_Hash) to the beacon signal BS as described above.However, the probability that the time slot s1 will be actually used tosend a response signal is lower than the probability for other timeslots. The occurrence of collision between a response signal and thenoninteractive data DINF as a result of the transmission of thenoninteractive data DINF in the time slot s1 is limited to the case inwhich the stylus 100 communicates the noninteractive data DINF onceevery plurality of frames F at the same time as another (new) stylus 100happens to enter the sensing range SR and to send a response signal tothe beacon signal BS. Therefore, there is practically no problem even ifthe stylus 100 sends the noninteractive data DINF in the time slot s1,and the time slots that are available in limited quantity can beefficiently used. In addition, the time slots s3, s7, s11, and s15 canbe used for transmission of the other data D (interactive data DF) bynot transmitting the noninteractive data DINF in the time slot s15 andreleasing the time slot s15. In this case, the time slots s2, s6, s10,and s14 and the time slots s3, s7, s11, and s15 can be assigned todifferent styluses 100. This allows the plurality of styluses 100 tosend the interactive data DF at the transmission periods T (i.e.,through time division multiplexing).

FIG. 20 is a diagram illustrating an example of allocation of time slotsto the interactive data DF and the noninteractive data DINF when theinteractive data DF includes the custom data CD. FIG. 20 depicts a casein which the interactive data DF includes the 11-bit pen pressure valueTiP, the 2-bit barrel button state BB, the 1-bit inversion Inv, and the8-bit custom data CD. It should be noted that the values of the customdata flag CDf and the custom data size CDS depicted in FIG. 9 are both1. The size of the interactive data DF in this case is 22 bits, which isa size larger than 16 bits that can be sent in one time slot. Therefore,the stylus 100 sends the interactive data DF using two consecutive timeslots as illustrated in FIG. 20. Using such allocation of time slotspermits transmission at the fixed period T even if the size of theinteractive data DF is larger than the size that can be sent in one timeslot.

FIG. 21 is a diagram illustrating an example of allocation of time slotsand frequencies to the interactive data DF and the noninteractive dataDINF when the interactive data DF includes the orientation OR. In theexample depicted in the same figure, two frequencies f0 and fl are used,and three time slots are used at the frequency f0, and four time slotsare used at the frequency fl to send the interactive data DF. Then, theorientation OR is sent using two time slots at the frequency f0 andthree time slots at the frequency fl or a total of five time slots. Suchallocation of time slots and frequencies permits transmission at thefixed period T even if the size of the interactive data DF is largeenough to be sent using seven time slots. It should be noted, however,that the interval T in this case is longer than the interval T in FIG.18 to FIG. 20 as can be understood by comparing FIG. 21 against FIG. 18to FIG. 20. It should be noted that if such frequency multiplexingcannot be used, the data may be sent using a total of seven time slotsthat are spread across the two or more frames F.

<A2-3. Operation of the Stylus 100 after Leaving the Sensing Range SR>

Referring back to FIG. 14, if the beacon signal BS is no longer detectedin step S10 (negative determination in step S10), the stylus 100determines whether or not the consecutive non-detection counter value islarger than a given threshold Th (step S14). When determining that theconsecutive non-detection counter value is not larger, the stylus 100will increment the consecutive non-detection counter value by 1 (stepS15) and returns to step S10. On the other hand, when the stylus 100determines that the consecutive non-detection counter value is larger instep S14, the pen raising operations C4 and C5 illustrated in FIG. 1 areperformed. This means that the stylus 100 has moved out of the sensingrange SR, and the stylus 100 is restored to step S2, that is, the statein which the stylus 100 may accept replacement of the refill body 121 oroperation of the tail switch 103 by the user.

Next, FIG. 15 is a diagram illustrating a flow of operation of thesensor controller 31. The sensor controller 31 initiates the operationdescribed in section “B 1” below after power is turned on.

<B1. Reception of the Capability Information CP>

The sensor controller 31 repeatedly send the beacon signal BS in thetime slot s0 (step S20) and each time goes on standby to wait for aresponse signal Ack from the stylus 100 in the time slot s1 (step S21).

When receiving the downlink signal DS which is the response signal Ack(i.e., downlink signal DS received in the time slot s1) (affirmativedetermination in step S21) in step S21, the sensor controller 31 willtreat the data included in the received response signal Ack as the hashvalue CP_Hash of the capability information CP (step S22). Then, thesensor controller 31 determines whether or not the hash value CP_Hashmatches any one of the hash values CP_Hash stored in the past in stepS33 which will be described later (step S23). When determining thatthere is the matching hash value CP_Hash, the sensor controller 31 willdetermine details of the capability information CP (including the dataformat DFmt) of the currently approaching stylus 100 using thecapability information CP stored in association with that hash valueCP_Hash (step S30).

On the other hand, when determining in step S23 that there is nomatching hash value CP_Hash, the sensor controller 31 will accumulatethe data included in the response signal Ack as part of the capabilityinformation CP (step S24). Then, the sensor controller 31 determineswhether or not all the capability information CP has been accumulated asa result of the repetition of the processes up to this point (step S25).When determining that all the capability information CP has beenaccumulated, the sensor controller 31 will determine details of thecapability information CP (including the data format DFmt) of thecurrently approaching stylus 100 (step S30). On the other hand, whendetermining that all the capability information CP has yet to beaccumulated, the sensor controller 31 will return to step S20 to repeatthe transmission of the beacon signal BS.

The sensor controller 31 that determined the details of the capabilityinformation CP in step S30 derives the hash value thereof and stores thehash value in a storage area in association with the capabilityinformation CP as associated data (step S33). The storage area of theassociated data created as described above (associated data storagearea) can be implemented as a so-called hash table that retains valuesin relation to hash values as keys.

Next, the sensor controller 31 obtains the refill body type ID includedin the capability information CP. Then, the sensor controller 31 sets aposition deriving parameter corresponding to the obtained refill bodytype ID (step S34). The position deriving parameter is a parameter usedby the sensor controller 31 to derive the position of the stylus 100from the data signal received by the sensor 30 and varies depending onthe shape of the electrode 102. For example, the electrode 102 of therefill body 121A depicted in FIG. 5A and the electrode 102 of the refillbody 121B depicted in FIG. 5B differ in the manner in which the datasignal spreads on the touch surface 3 a. Therefore, the range of datasignals, which the sensor controller 31 should cover when deriving theposition, varies depending on the type of electrode 102. On the otherhand, as for the refill body 121C depicted in FIG. 5C, only the datasignal sent out from the electrode 102-1 is used to derive the position,and the data signal sent out from the electrode 102-2 is used to detectthe inclination of the stylus 100. Therefore, the sensor controller 31needs to distinguish between the data signals sent from the electrodes102-1 and 102-2, respectively, based for example on the receptionintensities of the respective data signals. The position derivingparameter specifies a different position deriving method depending onthe shape of the electrode 102, and the sensor controller 31 isconfigured to derive the position of the stylus 100 by processing thedata signal received from the stylus 100 based on the position derivingparameter as illustrated in step S42, which will be described later.

<B2. Reception of the Data D>

Next, the sensor controller 31 sends the beacon signal BS again in thetime slot s0 (step S40). Then, the sensor controller 31 determineswhether or not some kind of data signal has been detected in time slotsother than the time slots s0 and s1 (step S41), and when determiningthat a data signal has been detected, the sensor controller 31 willderive the position of the stylus 100 based on the position derivingparameter, which has been set in step S34 (step S42), and reset aconsecutive non-reception counter to 0 (step S43). Thereafter, thesensor controller 31 receives the interactive data DF by extracting theinteractive data DF from the detected data signal (step S44). The sensorcontroller 31 also receives the noninteractive data DINF once everyplurality of frames F by extracting the noninteractive data DINF fromthe detected data signal (step S45).

On the other hand, when determining in step S41 that the data signal hasyet to be detected, the sensor controller 31 will determine whether ornot the consecutive non-reception counter value is larger than the giventhreshold Th (step S46). When determining that the consecutivenon-reception counter value is not larger, the sensor controller 31 willincrement the consecutive non-reception counter value by 1 (step S47)and return to step S40. Meanwhile, when determining in step S46 that theconsecutive non-reception counter value is larger, this means that thestylus 100 has moved out of the sensing range SR. Therefore, the sensorcontroller 31 returns to step 20 to continue with the processes.

As described up to this point, according to the method using the stylus100 and the sensor controller 31, the stylus 100, and the sensorcontroller 31 according to the present embodiment, the stylus 100 sendsthe capability information CP including the refill body type ID inresponse to a given trigger that occurs when the pen lowering operationC1 takes place, i.e., in response to reception of the beacon signal BS,thus making it possible to send the refill body type ID from the stylus100 to the sensor controller 31 only when the pen lowering operation C1is performed. Therefore, it is possible to efficiently send the refillbody type ID from the stylus 100 to the sensor controller 31.

Also, once the capability information CP is shared with the sensorcontroller 31, it is possible to notify the sensor controller 31 of thecapability information CP by sending only the hash value CP_Hash ratherthan the entire capability information CP. As a result, even under acondition in which the stylus 100 frequently enters and leaves thesensing range SR in a repeated manner, the time required for the sensorcontroller 31 to identify the capability information CP can beshortened.

When the hash value CP_Hash is sent in step S8 in FIG. 14, the stylus100 performs a process of deriving the hash value CP_Hash from thecapability information CP prior to the transmission, and this derivationmay be performed based on the entire capability information CP or basedon only part thereof. A detailed description will be given below of theprocess of deriving the hash value CP_Hash based on only part of thecapability information CP.

First, the capability information CP depicted in FIG. 8 includes firstcapability information that is not changed by user operation or settingfrom the sensor controller 31 and second capability information that canbe changed by user operation or setting from the sensor controller 31.First capability information is, for example, information indicatingtypes of sensors such as pen pressure sensor and angular sensor of thestylus 100; information indicating whether or not the stylus 100 has thebarrel button 104 (information indicated by the number of barrel buttonsBBN depicted in FIG. 9; BBN=0 indicates that the stylus 100 has nobarrel button 104, and BBN 0 indicates that the stylus 100 has thebarrel button(s) 104); information indicating whether or not the stylus100 has an inclination detection sensor or a twist detection sensor(information indicated by the orientation code ORC depicted in FIG. 10;for example, ORC=1 indicates that the stylus 100 has no twist detectionsensor, and ORC=2 indicates that the stylus 100 has a twist detectionsensor); and information indicating whether or not the stylus 100 hasany other sensor (information indicated by the custom data flag CDfdepicted in FIG. 9). Information indicating whether the stylus 100 iscapable of specifying the color of a line drawn by the stylus 100(information indicated by the color Col depicted in FIG. 8) may also beincluded in first capability information. Although not depicted in FIG.8 or other figures, the capability information CP can includeinformation identifying the function assigned to each of the one or morebarrel buttons 104. Such information may be a piece of first capabilityinformation. This information includes information for distinguishingbetween primary and secondary barrel buttons 104 when there are twobarrel buttons 104, or information indicating that the style Styl turnsinto an eraser while the barrel button 104 is held pressed, for example.

On the other hand, second capability information includes the refillbody type ID and other information identifying, for example, the colorand width of a line drawn by the stylus 100 or the brush type such as apencil type and a ballpoint pen type. These are indicated by the colorCol and the style Styl depicted in FIG. 8. Because the user identifier(UID) is information that may be used to identify inking informationsuch as color and width, the user identifier (UID) may also be used asthe second capability information.

When deriving the hash value CP_Hash, the stylus 100 may derive the hashvalue CP_Hash based only on the portion of the capability information CPrelating to second capability information. This makes it possible toreduce the possibility that the same hash value CP_Hash may be derivedfor different pieces of the capability information CP (possibility thatthe hash values may collide). For example, it is possible to downsizeinformation that serves as a source for deriving the hash value, ascompared to when the hash value CP_Hash is derived based on the entirecapability information CP, by deriving the hash value CP_Hash based onlyon the portion relating to the second capability information. Thesmaller the size of information that serves as a source for deriving thehash value, the smaller the possibility of collision between hashvalues. Therefore, it is possible to reduce the possibility of collisionbetween hash values by taking the above measure.

On the other hand, when determining in step S23 depicted in FIG. 15 thatno hash value matching the received hash value CP_Hash is stored in theassociated data storage area, the sensor controller 31 may send arequest to send the entire capability information CP to the stylus 100.It should be noted that this transmission should preferably be conductedby including the above request as a command in the beacon signal BS.When this request is received, it is only necessary for the stylus 100to determine that the stylus 100 has yet to be paired in step S6depicted in FIG. 14. Doing so makes it possible to send the entirecapability information CP from the stylus 100 to the sensor controller31.

Alternatively, the sensor controller 31 may decide not to accept part orwhole of the capability information CP sent by the stylus 100 inaccordance with its own resources, rather than unconditionally acceptingthe capability information CP. Still alternatively, the sensorcontroller 31 may determine the time slots to use for transmission ofthe data D on its own. A description will be given below in this regardwith reference to FIG. 22.

FIG. 22 is a diagram illustrating a modification example of the flow ofoperation of the sensor controller 31 depicted in FIG. 15. FIG. 22depicts only an extracted part of the flow depicted in FIG. 15.

As illustrated in FIG. 22, when receiving all the capability informationCP in step S25 or obtaining the capability information CP from theassociated data storage area in step S23, the sensor controller 31according to this modification example will temporarily determine thedata format DFmt based on the received or obtained capabilityinformation CP and on information on available resources (step S26).Information on available resources refers, for example, to time slotvacancies. Then, the sensor controller 31 sends the command thatspecifies the temporarily determined data format DFmt to the stylus 100as part of the beacon signal BS (step S27).

Thereafter, the sensor controller 31 attempts to detect the responsesignal Ack sent by the stylus 100 (step S28), and when the responsesignal Ack is not detected, the sensor controller 31 will bring itsprocess back to step S20 depicted in FIG. 15 by assuming that the stylus100 has moved out of the sensing range SR or did not accept thetemporarily determined data format DFmt. On the other hand, when theresponse signal Ack is received in step S28, the sensor controller 31will determine the details of the capability information CP (includingthe data format DFmt) based on the temporarily determined details (stepS30).

After step S30, the sensor controller 31 determines offset informationand interval information based on the determined data format DFmt (stepS31). Offset information is information that indicates, of the pluralityof time slots forming the frame F, those used to send at least part ofthe interactive data DF. More specifically, the offset informationindicates the distance in time between the first time slot that sendsthe interactive data DF out of the plurality of time slots forming theframe F and the beginning of the frame F. In the examples illustrated inFIG. 18, FIG. 20, and FIG. 21, for example, the offset information is 2,and in the example illustrated in FIG. 19, the offset information is 3.On the other hand, interval information is information that indicatesthe transmission period of the interactive data DF. In the examplesillustrated in FIG. 18 to FIG. 20, for example, the interval informationis 4, and in the example illustrated in FIG. 21, the intervalinformation is 8. In short, the offset information and the intervalinformation specify when a certain piece of individual interactive dataof the one or more pieces of individual interactive data is sent. Theoffset and interval information, together with the data format DFmt,defines the format that specifies the configuration of the data signalincluding the data D. Unlike the offset information, the intervalinformation can be represented by how often the transmission isperformed, and can be indicated by an identifier indicating thetransmission period or how frequently the transmission is performed.

After determining offset information and interval information in stepS31, the sensor controller 31 sends a command that indicates thedetermined offset information and interval information to the stylus 100as part of the beacon signal BS (step S32). From this step onward, thestylus 100 sends the interactive data DF using the time slot indicatedby the specified offset information and interval information.

As described above, the sensor controller 31 may decide on thecapability information CP of the stylus 100 as well as the time slot tobe used by the stylus 100 to send the data D. This way, the sensorcontroller 31 may take the initiative in communicating with the stylus100.

A description will be given next of the system 1 according to a secondembodiment of the present invention. The system 1 according to thepresent embodiment differs from the system 1 according to the firstembodiment in that two hash values are used as hash values of thecapability information CP. In the description given below, the samecomponents as those in the first embodiment are denoted by the samereference symbols, and a description will be given with focus ondifferences from the first embodiment.

FIG. 23 is a diagram illustrating a flow of operation of the stylus 100and the sensor controller 31 according to the present embodiment. Thesame figure illustrates a flow of operation relating to the process inwhich the sensor controller 31 receives the capability information CPfrom the stylus 100. A description will be given below of the operationof the stylus 100 and the sensor controller 31 according to the presentembodiment with reference to FIG. 23.

First, when power is turned on or a change that affects the hash valueis made to the capability information CP (corresponds to affirmativedetermination in step S2 of FIG. 14), the stylus 100 will derive twohash values #1 and #2 (first and second hash values) based on its owncapability information CP (steps S50 and S51). The two hash values #1and #2 may be derived using two different kinds of hash functions(algorithms) such as 13-bit CRC and 16-bit FNV. Alternatively, higherand lower order bit strings of a hash value derived by a single hashfunction may be used respectively as the hash values #1 and #2. Anotherpossible process is to derive the hash value #1 based on the firstcapability information descried above and derive the hash value #2 basedon the second capability information.

After entering the sensing range SR of the sensor controller 31 (referto FIG. 1) and detecting the beacon signal BS sent by the sensorcontroller 31 (steps S60 and S52), the stylus 100 sends only the hashvalue #1 first (step S53). This transmission is conducted by includingthe hash value #1 in a response signal to the beacon signal BS.

When detecting the response signal to the beacon signal BS (step S61),the sensor controller 31 will extract the hash value #1 (or theinformation deemed to be the has value #1) therefrom and determinewhether or not the hash value #1 is stored in the associated datastorage area (step S62). When not detecting the response signal in stepS61, the sensor controller 31 will return to step S60 to send the beaconsignal BS again in the next frame.

When determining in step S62 that the hash value #1 is not stored in theassociated data storage area, the sensor controller 31 will read thecapability information CP from the stylus 100 (step S63). This readingis conducted specifically by including a command Get (CP) indicating arequest for the capability information CP in the beacon signal BS to besent in the next frame. When the stylus 100 sends the capabilityinformation CP in response thereto (step S54), the sensor controller 31derives the hash value #2 based on the received capability informationCP and stores the hash value #2 in the associated data storage area inassociation with the received hash value #1 and capability informationCP (step S64). It should be noted that the sensor controller 31 mayderive the hash value #1 anew in this step S64.

On the other hand, when determining in step S62 that the hash value #1is stored in the associated data storage area, the sensor controller 31will read the hash value #2, stored in association with the receivedhash value #1, and send the hash value #2 to the stylus 100 (step S65).This transmission is also conducted by including the read hash value #2in the beacon signal BS to be sent in the next frame. When receiving thehash value #2 sent as described above, the stylus 100 will determinewhether or not the hash value #2 matches the hash value #2 derived instep S51 (step S56). When the two values match, the stylus 100 will sendthe response signal Ack, and when the two values do not match, thestylus 100 will send a fail signal Fail. These transmissions areconducted by including the response signal Ack or the fail signal Failin a response signal to the beacon signal BS. Then, when sending thefail signal Fail, the stylus 100 will return to step S52 to continuewith the processes, and when sending the response signal Ack, the stylus100 will terminate the detection process of the sensor controller 31 toproceed with the data signal transmission process described above(processes from step S10 onward depicted in FIG. 14). The sensorcontroller 31 determines whether the response signal Ack has beendetected in response to the hash value #2 sent in step S65 (step S66).When detecting the response signal Ack, the sensor controller 31 willterminate the detection process of the stylus 100 to proceed with thedata signal reception process (processes from step S40 onward depictedin FIG. 15), and when not detecting the response signal Ack (or whendetecting the fail signal Fail), the sensor controller 31 will return tostep S63 and proceed with the capability information CP reading processagain.

As described above, the system 1 according to the present embodimentallows the sensor controller 31 to reconfirm a match between thecapability information CP stored in its own associated data storage areaand the capability information CP available with the stylus 100 usingthe hash value #2 stored in association with the received hash value #1.This makes it possible to engage in communication using the correctcapability information CP in a more reliable manner.

Although preferred embodiments of the present invention have beendescribed above, the present invention is in no way limited by theseembodiments, and it is a matter of course that the present invention canbe carried out in various forms.

For example, although, in each of the above embodiments, the derivationof coordinate data (X,Y) indicating the position of the stylus 100 andthe transmission of the interactive data DF and so on are conducted byusing the same downlink signal DS, they may be accomplished by thedifferent downlink signals DS as illustrated in FIG. 24. FIG. 24 depictsan example in which a position signal dedicated for deriving coordinatedata (X,Y) and the interactive data DF are sent in two differentdownlink signals DS, respectively, in a time-divided manner. The sensorcontroller 31 derives coordinate data (X,Y) indicating the position ofthe stylus 100 based only on the first downlink signal DS, andthereafter suitably obtains the interactive data DF sent by the stylus100.

In each of the above embodiments, an example was described in which thestylus 100 and the sensor controller 31 communicated bidirectionally. Ina further aspect, the present invention is suitably applicable in aunidirectional communication embodiment in which the stylus 100unidirectionally communicates with the sensor controller 31. A detaileddescription will be given below.

FIG. 25 is a diagram illustrating a flow of operation of the stylus 100according to a modification example of the present invention. FIG. 26 isa diagram illustrating a flow of operation of the sensor controller 31according to the present modification example.

A description will be given first of the operation of the stylus 100with reference to FIG. 25. First, as for steps S1 to S3, the operationis the same as that described with reference to FIG. 14. After step S3,the stylus 100 according to the present modification example determineswhether or not the pen pressure value detected by the operation statedetection circuitry 105 has reached a value (a defined value) largerthan 0 (step S70), instead of detecting the beacon signal BS (step S4)as depicted in FIG. 14. The beacon signal BS is not detected because thesensor controller 31 in the present modification example does not sendthe beacon signal BS. The pen pressure value larger than 0 normallymeans that the pen moving operation C3 (refer to FIG. 1) is in progressfollowing the pen touch operation C2 (refer to FIG. 1). Therefore, thedetection of the pen touch operation C2 is substantially performed instep S70.

The stylus 100 according to the present modification example sendsinformation on the capability information CP including the refill bodytype ID in response to an affirmative determination in step S70 (i.e.,detection of the pen touch operation C2) used as a trigger (a triggerthat occurs when the pen lowering operation takes place) (step S71).Information sent here may be the capability information CP itself orinformation indicating that no change has been made to the capabilityinformation CP (non-change information). Also, if it is possible tostore the capability information CP in the sensor controller 31 inadvance, the capability information CP may be in the form of informationthat allows for the sensor controller 31 to identify the capabilityinformation CP, such as the hash value CP_Hash or the user identifierUID described above. If the stylus 100 is unable to send all thecapability information CP in one shot because of its large size, thestylus 100 may send the capability information CP a plurality of timesin batches as in step S7 depicted in FIG. 14.

The processes after the transmission of information on the capabilityinformation CP in step S71 are basically the same as those from step S10onward described in FIG. 14. It should be noted, however, that, in thepresent modification example, it is determined whether or not the penpressure value is 0 or not, in place of the detection of the beaconsignal BS in step S10 (step S72). The reason why the beacon signal BS isnot detected is the same as in step S70 (i.e., the beacon signal BS isnot sent by the sensor controller 31). The pen pressure value equal to 0normally means that the pen raising operations C4 and C5 (refer toFIG. 1) have been performed. Therefore, the detection of the pen raisingoperations C4 and C5 is substantially performed in step S72.

A description will be given next of the operation of the sensorcontroller 31 according to the present modification example withreference to FIG. 26. The sensor controller 31 according to the presentmodification example detects a signal from the stylus 100 (step S80).Then, the sensor controller 31 determines first whether or not thecapability information CP (or part thereof) is included in that signal(step S81). When the capability information CP (or part thereof) isincluded, the sensor controller 31 accumulates the data included in thesignal as the capability information CP (or part thereof) (step S83).Then, the sensor controller 31 determines whether or not all thecapability information CP has been accumulated as a result of therepetition of the processes up to this point (step S84). Whendetermining that all the capability information CP has been accumulated,the sensor controller 31 will determine details of the capabilityinformation CP (including the data format DFmt) of the currentlyapproaching stylus 100 based on the capability information CPaccumulated in step S83 (step S85). On the other hand, when determiningthat all the capability information CP has yet to be accumulated, thesensor controller 31 will return to step S80 to repeat the detection ofa signal.

On the other hand, when determining in step S81 that the capabilityinformation CP (part thereof) is not included, the sensor controller 31will determine details of the capability information CP (including thedata format DFmt) of the currently approaching stylus 100 based on aprevious accumulation result (step S86). Describing specifically, whennon-change information described above (i.e., information indicatingthat no change has been made to the capability information CP) isincluded in the signal from the stylus 100, the sensor controller 31determines details of the capability information CP of the currentlyapproaching stylus 100 based on the latest capability information CPthat was received and accumulated previously. On the other hand, whenconfigured to be able to accumulate the capability information CP inassociation with the hash values CP_Hash, the sensor controller 31 readsthe capability information CP associated with the hash value CP_Hashincluded in the signal from the stylus 100 and determines details of thecapability information CP of the currently approaching stylus 100 basedon the read capability information CP. Further, when configured to beable to accumulate the capability information CP in association with theuser identifiers UID, the sensor controller 31 reads the capabilityinformation CP associated with the user identifier UID included in thesignal from the stylus 100 and determines details of the capabilityinformation CP of the currently approaching stylus 100 based on the readcapability information CP.

The processes after the determination of details of the capabilityinformation CP in step S85 or step S86 are basically the same as thosefrom step S34 onward described in FIG. 15. It should be noted, however,that because the sensor controller 31 according to the presentmodification example does not send any signals, the beacon signal BS isnot sent in step S40. Also, the process in step S33 depicted in FIG. 15,that is, the process of deriving the hash value of the capabilityinformation CP and storing the hash value in the storage area inassociation with the capability information CP as associated data mayneed not be performed. The sensor controller 31 according to the presentmodification example may store a hash value and the capabilityinformation CP in association pursuant to an explicit user instruction,but need not do so during lowering of the pen (unless there is a userinstruction). Even if a hash value is calculated based on the capabilityinformation CP, which is received during lowering of the pen, and isstored in association with the capability information CP, the stylus 100has no way of knowing the condition of the sensor controller 31 (becausethere is no communication from the sensor controller 31). Therefore, thestylus 100 cannot determine whether the capability information CP hasbeen correctly conveyed to the sensor controller 31 by simply sendingonly the hash value. In order to ensure that the capability informationCP is conveyed correctly, therefore, the capability information CPitself should be sent. This is true also when the user identifier UIDand the capability information CP are stored in association. When thesensor controller 31 according to the present modification example is tostore the hash value or the user identifier UID in association with thecapability information CP, it should do so pursuant to a clear(explicit) user instruction rather than during lowering of the pen.

In the present modification example, the stylus 100 is configured tosend the capability information CP in response to a trigger of detectingthat the pen pressure value becomes greater than 0 (i.e., detection ofthe pen touch operation C2). Such a trigger may be used also in thefirst and second embodiments described above. For example, if the stylus100 is configured to determine whether the pen pressure value has becomegreater than 0 in addition to determining whether the beacon signal BShas been detected in step S10 of FIG. 14 and step S52 of FIG. 23, it ispossible to ensure that the stylus 100 sends the capability informationCP either when the beacon signal BS is detected or when the pen pressurevalue becomes greater than 0.

Although an example was described in each of the above embodiments inwhich the refill body type ID is used by the sensor controller 31 to seta position deriving parameter, the refill body type ID may also be usedfor other purposes in addition to the purpose of setting a positionderiving parameter. An example thereof will be described below.

FIG. 27A and FIG. 27B are diagrams illustrating the stylus 100 accordingto modification examples of the present invention. FIG. 27A illustratesa case in which a refill body 121D having a hard pen tip is attached tothe stylus 100, and FIG. 27B illustrates a case in which a refill body121E having a soft pen tip like a brush is attached to the stylus 100.It should be noted that the electrode 102 is not depicted in FIG. 27Aand FIG. 27B.

In the example depicted in FIG. 27A, when the user applies a pressure P(or force P) to the touch surface 3 a via the pen tip, all the pressureP is directly applied to the operation state detection circuitry 105.Therefore, the pen pressure value sent from the stylus 100 to the sensorcontroller 31 becomes a value P equal to the pressure applied to the pentip by the touch surface 3 a. In the example depicted in FIG. 27B, onthe other hand, even when the user applies the pressure P to the touchsurface 3 a via the pen tip, the pressure applied to the operation statedetection circuitry 105 is smaller than P (P/3 in the example depicted).The reason for this is that part of the pressure P to be conveyed to theoperation state detection circuitry 105 is absorbed by the flexibilityof the brush and by the pressure (or force) generated between thehousing and the refill body 121E. Therefore, the pen pressure value sentfrom the stylus 100 to the sensor controller 31 is smaller than P, suchas P/3, in a special nonlinear function.

As described above, a pen pressure value smaller than the original penpressure value P may be conveyed to the sensor controller 31 dependingon the type of the refill body 121. The sensor controller 31 accordingto the present modification example uses the refill body type ID inorder to convert the pen pressure value, which is conveyed as a valuesmaller than the original pen pressure value (e.g., P/3), into theoriginal pen pressure value (e.g., P, hereinafter referred to as a “penpressure level”).

Describing in detail, the sensor controller 31 according to the presentmodification example stores a function (pen pressure curve; method forderiving a pen pressure level) for converting the pen pressure valuereceived from the stylus 100 into a pen pressure level for each of therefill body types ID. Then, the sensor controller 31 selects a penpressure curve corresponding to the refill body type ID received fromthe stylus 100 and converts the pen pressure value received from thestylus 100 into a pen pressure level using the selected pen pressurecurve.

For example, the sensor controller 31 stores Pb=Pa as a pen pressurecurve for the refill body 121D depicted in FIG. 27A, where Pa is the penpressure value received from the stylus 100, and Pb is the pen pressurelevel after conversion. On the other hand, the sensor controller 31stores Pb=Pa×3 as a pen pressure curve for the refill body 121E depictedin FIG. 27B. As a result, the pen pressure level Pb that appears whenthe user applies the pressure P to the touch surface 3 a via the pen tipis P for both the refill body 121D (=P) and the refill body 121E(=P/3×3). Thus, the present modification example allows the sensorcontroller 31 to obtain the original pen pressure value regardless ofthe type of the refill body 121.

As a further example, it is possible to use refill body information soas to identify the appropriate electrode or signal distribution shapefor detection of not only the pen pressure but also the inclinationangle and other data of the stylus 100. In these cases also, the presentinvention allows efficient conveyance of the refill body information tothe sensor controller 31 separately from other data that is repeatedlysent.

DESCRIPTION OF REFERENCE SYMBOLS

-   -   1 System    -   3 Electronic apparatus    -   3 a Touch surface    -   30 Sensor    -   30X, 30Y Linear electrode    -   31 Sensor controller    -   32 System controller    -   40 Selecting circuit    -   41 x, 41 y Conductor selection circuit    -   44 x, 44 y Switch    -   49 Detecting circuit    -   50 Receiving circuit    -   51 Amplifying circuit    -   52 Detecting circuit    -   53 AD converter    -   60 Transmitting circuit    -   61 Control signal supply circuit    -   62 Switch    -   63 Direct spreading circuit    -   64 Spreading code holding circuit    -   65 Transmitting guard circuit    -   70 Logic circuit    -   80 MCU    -   100 Stylus    -   101 Battery    -   102 Electrode    -   103 Tail switch    -   104 Barrel button    -   105 Operation state detection circuitry    -   106 Stylus controller IC    -   110 Communication circuitry    -   111 Capability information updating circuitry    -   112 Interactive data acquisition circuitry    -   113 Noninteractive data acquisition circuitry    -   120 Refill body holder    -   121, 121A to 121C Refill body    -   123, D1, D0, T1 to T3 Terminal    -   BB Barrel button state    -   BBN Number of barrel buttons    -   BL Battery level    -   BS Beacon signal    -   C1 Pen lowering operation    -   C2 Pen touch operation    -   C3 Pen moving operation    -   C4, C5 Pen raising operation    -   CBS Custom button size    -   CD Custom data    -   CDf Custom data flag    -   CDS Custom data size    -   COS Custom orientation size    -   CP Capability information    -   CP_Hash Hash value    -   CPS Custom pen pressure size    -   Col Color    -   D Data    -   DF Interactive data    -   DFmt Data format    -   DINF Noninteractive data    -   DS Downlink signal    -   F Frame    -   H1 to H3 Recessed portion    -   L1 to L3 Wiring segment    -   OCT Orientation code table    -   OR Orientation    -   ORC Orientation code    -   ORR Orientation resolution    -   PL Number of pen pressure reading levels    -   Rx Receiving circuit (Receiver)    -   SR Sensing range    -   Styl Style    -   TaP Tangential pen pressure value    -   TaPf Tangential pen pressure flag    -   TiP Pen pressure value    -   Tx Transmitting circuit (Transmitter)

The various embodiments described above can be combined to providefurther embodiments. All of the U.S. patents, U.S. patent applicationpublications, U.S. patent applications, foreign patents, foreign patentapplications and non-patent publications referred to in thisspecification and/or listed in the Application Data Sheet areincorporated herein by reference, in their entirety. Aspects of theembodiments can be modified, if necessary to employ concepts of thevarious patents, applications and publications to provide yet furtherembodiments.

These and other changes can be made to the embodiments in light of theabove-detailed description. In general, in the following claims, theterms used should not be construed to limit the claims to the specificembodiments disclosed in the specification and the claims, but should beconstrued to include all possible embodiments along with the full scopeof equivalents to which such claims are entitled. Accordingly, theclaims are not limited by the disclosure.

1. A method of using an active stylus and a sensor controller, themethod comprising: the active stylus, in response to a triggerindicative of a pen lowering operation, sending refill body informationindicating a type of a refill body that forms a pen tip of the activestylus; the sensor controller receiving the refill body information andidentifying the refill body type of the active stylus; the active stylusrepeatedly sending a data signal including a pen pressure value appliedto the refill body; and the sensor controller deriving a position of theactive stylus based on the data signal using a position deriving methodthat corresponds to the identified refill body information.
 2. Themethod according to claim 1, wherein the data signal does not includethe refill body information.
 3. The method according to claim 1, whereinthe trigger is detection, by the active stylus, of an uplink signal sentfrom the sensor controller.
 4. The method according to claim 3, whereinthe active stylus sends the refill body information in a response signalto the uplink signal.
 5. The method according to claim 1, wherein thetrigger is that the pen pressure value has reached a threshold value. 6.The method according to claim 1, wherein the refill body information ispart of capability information which may change while the active stylusis located outside a sensing range of the sensor controller.
 7. Themethod according to claim 6, wherein the active stylus sends the refillbody information by sending the capability information.
 8. The methodaccording to claim 6, wherein the active stylus sends the refill bodyinformation by sending a hash value of data including the capabilityinformation.
 9. The method according to claim 1, wherein the refill bodyinformation is part of a unique identifier that identifies the activestylus, and the active stylus sends the refill body information bysending the unique identifier.
 10. The method according to claim 1,wherein the refill body information includes information indicatingwhether an electrode used by the active stylus for signal transmissionis located inside or outside the refill body.
 11. The method accordingto claim 1, wherein the refill body information includes informationidentifying a number and arrangement of electrode(s) used by the activestylus for signal transmission.
 12. The method according to claim 1,wherein the active stylus is configured such that the refill body isattachable and detachable.
 13. An active stylus, comprising: a pen tiphaving an electrode; transmitting circuitry coupled to the electrode andwhich, in operation, sends signals from the electrode to a sensorcontroller; and a controller coupled to the transmitting circuitry andwhich, in response to a trigger indicative of a pen lowering operation,controls transmission of refill body information indicating a type of arefill body that forms the pen tip to the sensor controller via thetransmitting circuitry, and controls repeated transmissions of datasignals to the sensor controller via the transmitting circuitry afterhaving sent the refill body information.
 14. The active stylus accordingto claim 13, comprising: detection circuitry coupled to the controllerand which, in operation, detects a pen pressure applied to the refillbody, wherein the data signal does not include the refill bodyinformation, but includes a pen pressure value applied to the refillbody.
 15. The active stylus according to claim 14, wherein the triggeris that the pen pressure value has reached a threshold value.
 16. Theactive stylus according to claim 14, wherein the refill body informationincludes information that identifies a pen pressure curve that convertsthe pen pressure value included in the data signal into a pen pressurelevel usable by the sensor controller.
 17. The active stylus accordingto claim 13, comprising: receiving circuitry coupled to the electrodeand which, in operation, receives signals from the sensor controller viathe electrode, wherein the trigger is detection, by the receivingcircuitry, of an uplink signal sent from the sensor controller.
 18. Theactive stylus according to claim 13, wherein the refill body informationis part of capability information which may change while the activestylus is located outside a sensing range of the sensor controller, andthe refill body information is sent as part of the capabilityinformation.
 19. A sensor controller, comprising: reception circuitrywhich, in operation, receives, from an active stylus, i) refill bodyinformation indicating a type of a refill body forming a pen tip of theactive stylus, and ii) a data signal including a pen pressure valueapplied to the refill body; and processing circuitry coupled to thereception circuitry and which, in operation, obtains the refill bodyinformation received from the active stylus via the reception circuitry,determines a position deriving method that corresponds to the obtainedrefill body information, and derives a position of the active stylusbased on the data signal using the determined position deriving method.20. The sensor controller according to claim 19, comprising:transmission circuitry coupled to the processing circuitry and which, inoperation, sends an uplink signal to the active stylus, wherein thereception circuitry receives the refill body information from the activestylus which has detected the uplink signal.
 21. The sensor controlleraccording to claim 19, wherein the processing circuitry, in operation,determines a pen pressure level deriving method that corresponds to theobtained refill body information, and derives a pen pressure level fromthe pen pressure value included in the data signal using the determinedpen pressure level deriving method.